Improved synthesis and hydrogen storage of a microporous metal-organic framework material

International Nuclear Information System (INIS)

Cheng Shaojuan; Liu Shaobing; Zhao Qiang; Li Jinping

2009-01-01

A microporous metal-organic framework MOF-5 [Zn 4 O(BDC) 3 , BDC = 1,4-benzenedicarboxylic] was synthesized with and without H 2 O 2 by improved methods based on the previous studies. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy and nitrogen adsorption, and their hydrogen storage capacities were measured. The synthesis experiments showed that H 2 O 2 favored the growth of high quality sample, large pore volume and high specific surface area. The measurements of hydrogen storage indicated that the sample with higher specific surface area and large pore volume showed better hydrogen storage behavior than other samples. It was suggested that specific surface area and pore volume influenced the capacity of hydrogen storage for MOF-5 material.

Fast Synthesis of Pt Nanocrystals and Pt/Microporous La2O3 Materials Using Acoustic Levitation

Science.gov (United States)

Yu, Yinkai; Qu, Shaohua; Zang, Duyang; Wang, Liuding; Wu, Hongjing

2018-02-01

Usually, we must use an appropriate support material to keep the metal species stable and finely dispersed as supported metal nanoparticles for industry application. Therefore, the choice of support material is a key factor in determining the dispersion and particle size of the noble metal species. Here, we report the synthesis of a single-atom Pt material in the solution and supported Pt nanoclusters on microporous La2O3 by a one-step acoustic levitation method without any pretreatment/modification of raw oxide. We have strongly contributed to the synthetic methodology of the surface/interfacial heterogeneous catalysts in this study, and this finding could open another door for synthesis of supported metal nanoparticles on porous materials for environmental catalysis.

Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

Science.gov (United States)

Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

2016-06-01

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microporous Organic Materials for Membrane-Based Gas Separation.

Science.gov (United States)

Zou, Xiaoqin; Zhu, Guangshan

2018-01-01

Membrane materials with excellent selectivity and high permeability are crucial to efficient membrane gas separation. Microporous organic materials have evolved as an alternative candidate for fabricating membranes due to their inherent attributes, such as permanent porosity, high surface area, and good processability. Herein, a unique pore-chemistry concept for the designed synthesis of microporous organic membranes, with an emphasis on the relationship between pore structures and membrane performances, is introduced. The latest advances in microporous organic materials for potential membrane application in gas separation of H 2 , CO 2 , O 2 , and other industrially relevant gases are summarized. Representative examples of the recent progress in highly selective and permeable membranes are highlighted with some fundamental analyses from pore characteristics, followed by a brief perspective on future research directions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The role of the nature of pillars in the structural and magnetic properties of magnetic pillared vlays

DEFF Research Database (Denmark)

Bachir, Cherifa; Lan, Yanhua; Mereacre, Valeriu

2011-01-01

of pillared clays by examining in detail the influence of the calcination temperature and the nature of different pillared clays on these properties. Magnetic layered systems from different pillared clays were prepared and characterized. Firstly, Ti-, Al-, and Zr-pillared clays (Ti-PILCs, Al-PILCs, and Zr......-PILCs, respectively) were produced at different calcination temperatures and then magnetic pillared clays (Ti-M-PILCs, Al-M-PILCs, and Zr-M-PILCs) were prepared at ambient temperature. The synthesis involves a reduction in aqueous solution of the original Fe-exchanged pillared clay using NaBH4. The structural....... Similar experiments with Al- and Zr-pillars have been discussed. A correlation between the XRF data, porosity, FF calculation, and magnetic properties led to the conclusion that the sample Al-M-PILC previously calcined at 500 degrees C was the most stable material after the magnetization process. The same...

Room temperature synthesis of heptazine-based microporous polymer networks as photocatalysts for hydrogen evolution.

Science.gov (United States)

Kailasam, Kamalakannan; Schmidt, Johannes; Bildirir, Hakan; Zhang, Guigang; Blechert, Siegfried; Wang, Xinchen; Thomas, Arne

2013-06-25

Two emerging material classes are combined in this work, namely polymeric carbon nitrides and microporous polymer networks. The former, polymeric carbon nitrides, are composed of amine-bridged heptazine moieties and showed interesting performance as a metal-free photocatalyst. These materials have, however, to be prepared at high temperatures, making control of their chemical structure difficult. The latter, microporous polymer networks have received increasing interest due to their high surface area, giving rise to interesting applications in gas storage or catalysis. Here, the central building block of carbon nitrides, a functionalized heptazine as monomer, and tecton are used to create microporous polymer networks. The resulting heptazine-based microporous polymers show high porosity, while their chemical structure resembles the ones of carbon nitrides. The polymers show activity for the photocatalytic production of hydrogen from water, even under visible light illumination. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microporous silica membranes

DEFF Research Database (Denmark)

Boffa, Vittorio; Yue, Yuanzheng

2012-01-01

Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

Synthesis and characterization of pillared bentonite with Al, AL/Fe and impregnated with Pd; Sintese e caracterizacao de bentonitas pilarizadas com Al, AL/Fe e impregnadas com Pd

Energy Technology Data Exchange (ETDEWEB)

Silva, Marcus Vinicius Costa; Pizarro, Alejandro Herrero; Molina, Carmen Belen, E-mail: marcus.ufpa@yahoo.com.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Instituto de Tecnologia. Faculdade de Engenharia Quimica; Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madri (Spain)

2017-10-01

In this work, a north american bentonite was pillared with Al and Al/Fe, creating the Al-PILC and Al-Fe-PILC, respectively. Then the Pd was impregnated in the materials, generating Pd-Al-PILC and Pd-Al-Fe-PILC, respectively. The samples were characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and N{sub 2} adsorption at 77 K to determine the specific surface area by BET method (Brunauer - Emmett - Teller). There was an increase in the basal spacing of bentonite from 12.4Å in the original sample to 17.81Å in the Al-Fe-PILC, 17.20Å in Pd-Al-PILC and 17.05Å in the Pd-Al-Fe-PILC. The specific surface area increased from 19.05m{sup 2}/g in the original sample to 173.49m{sup 2}/g in Al-Fe-PILC, 101.31m{sup 2}/g to Pd-Al-PILC and 92m{sup 2}/g in Pd-Al-Fe-PILC. The pillaring process was successful and the synthesized materials have great potential for use as catalysts. (author)

Electromagnetic micropores: fabrication and operation.

Science.gov (United States)

Basore, Joseph R; Lavrik, Nickolay V; Baker, Lane A

2010-12-21

We describe the fabrication and characterization of electromagnetic micropores. These devices consist of a micropore encompassed by a microelectromagnetic trap. Fabrication of the device involves multiple photolithographic steps, combined with deep reactive ion etching and subsequent insulation steps. When immersed in an electrolyte solution, application of a constant potential across the micropore results in an ionic current. Energizing the electromagnetic trap surrounding the micropore produces regions of high magnetic field gradients in the vicinity of the micropore that can direct motion of a ferrofluid onto or off of the micropore. This results in dynamic gating of the ion current through the micropore structure. In this report, we detail fabrication and characterize the electrical and ionic properties of the prepared electromagnetic micropores.

Synthesis of N-rich microporous carbon materials from chitosan by alkali activation using Na_2CO_3

International Nuclear Information System (INIS)

Ilnicka, Anna; Lukaszewicz, Jerzy P.

2015-01-01

Highlights: • The novel manufacturing procedure of nitrogen-rich carbon materials. • The biopolymer chitosan can be activated by sodium carbonate. • The effect of the addition of activator and the temperature of carbonization was investigated. • The N-rich carbon materials exhibit high specific surface area and microporous structure. - Abstract: The paper presents the first systematic study on the synthesis of nitrogen-rich nanoporous activated carbons by chitosan carbonization in the presence of a hard template (activator), i.e. Na_2CO_3. Carbonization process was carried out in the range of 600–900 °C under a flow of nitrogen. The effect of the addition of different volumes of activator and the temperature of carbonization on the development of specific surface area and pore structure (pore volume and median pore diameter) of the activated carbons was investigated. Additionally, the nitrogen content and nitrogen-containing surface species were determined by means of XPS and combustion elemental analysis. The nitrogen content was placed in the range of 2.4–13.1 wt.%. On the grounds of the low-temperature adsorption of nitrogen, it was found that obtained adsorption isotherms were of type-I, based on the IUPAC classification, which is typical for microporous materials.

“Stereoscopic” 2D super-microporous phosphazene-based covalent organic framework: Design, synthesis and selective sorption towards uranium at high acidic condition

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shuang; Zhao, Xiaosheng; Li, Bo; Bai, Chiyao; Li, Yang; Wang, Lei; Wen, Rui; Zhang, Meicheng; Ma, Lijian; Li, Shoujian, E-mail: sjli000616@scu.edu.cn

2016-08-15

Highlights: • Phosphorus element was first introduced into covalent organic frameworks (COFs). • Monomer in C{sub 3}-like spatial configuration was first used to construct COF materials. • A new 2D super-microporous phosphazene-based sorbent (MPCOF) was synthesized. • Separation of U (VI) by MPCOF at high acidic media (up to 1M HNO{sub 3}) was achieved. • Selectivity for U (VI) separation from multi-ion solution can reach unreported 92%. - Abstract: So far, only five primary elements (C, H, O, N and B) and two types of spatial configuration (C{sub 2}–C{sub 4}, C{sub 6} and T{sub d}) are reported to build the monomers for synthesis of covalent organic frameworks (COFs), which have partially limited the route selection for accessing COFs with new topological structure and novel properties. Here, we reported the design and synthesis of a new “stereoscopic” 2D super-microporous phosphazene-based covalent organic framework (MPCOF) by using hexachorocyclotriphosphazene (a P-containing monomer in a C{sub 3}-like spatial configuration) and p-phenylenediamine (a linker). The as-synthesized MPCOF shows high crystallinity, relatively high heat and acid stability and distinctive super-microporous structure with narrow pore-size distributions ranging from 1.0–2.1 nm. The results of batch sorption experiments with a multi-ion solution containing 12 co-existing cations show that in the pH range of 1–2.5, MPCOF exhibits excellent separation efficiency for uranium with adsorption capacity more than 71 mg/g and selectivity up to record-breaking 92%, and furthermore, an unreported sorption capacity (>50 mg/g) and selectivity (>60%) were obtained under strong acidic condition (1 M HNO{sub 3}). Studies on sorption mechanism indicate that the uranium separation by MPCOF in acidic solution is realized mainly through both intra-particle diffusion and size-sieving effect.

Fractal dimension and energetic heterogeneity of gold-modified Al-Fe-Ce pilc's

International Nuclear Information System (INIS)

Carriazo, J.G.; Molina, R.; Moreno, S.

2008-01-01

This paper studies the energetic and topographical changes that occur on the surface of a series of clays pillared with the mixed Al-Fe-Ce system and on the surface of solids synthesized by the deposition of gold nanoparticles over these pillared clays. The energetic heterogeneity of the solids was analyzed by means of the distribution of the adsorption potential, while the variations in the fractal dimension were determined from the nitrogen adsorption isotherms at 77 K, using the equation proposed by Avnir-Jaroniec. Results show the generation of microporous structures with important topographical modifications indicating an increase in the roughness (fractal geometry) of the surface of the solids as a consequence of the pillaring, revealing a positive effect of cerium addition in the synthesis process and the possible formation of nanoparticles of iron species and gold on the surface of pillared clays. The solids were also analyzed by transmission electron microscopy (TEM), confirming the formation of nanoparticles on the surface.

Sn-PILC: A novel Efficient and Recyclable Catalyst for One-pot Three Component Povarov’s Inverse-electron-demand Hetero Diels-Alder Reaction for a Facile Synthesis of Tetrahydropyranoquinoline Derivatives under Neat Conditions

Directory of Open Access Journals (Sweden)

Megha Rai

2016-07-01

Full Text Available The Povarov’s inverse-electron-demand hetero Diels–Alder one-pot three components reaction of aromatic aldehyde, aromatic amine with DHF has been developed using Sn-PILC as a catalyst under a neat condition which may helpful to society to get pharmacologically more active compounds. In the present study a novel series of tetrahydroquinoline 4(a-f were synthesized and characterized by IR, 1HNMR, 13CNMR, Mass spectral analysis and elemental analysis. The synthetic details and characterization results are discussed. DOI: http://dx.doi.org/10.17807/orbital.v8i3.801

Development of new microporous silica membranes for gas separation

International Nuclear Information System (INIS)

Camelia Barboiu; Alejandro Mourgues; Beatrice Sala; Serge de Perthuis; Camelia Barboiu; Alejandro Mourgues; Beatrice Sala; Anne Julbe; Jose Sanchez

2006-01-01

This paper presents the synthesis and the application of molecular sieving ceramic membranes to purify hydrogen or helium from various gas mixtures. The membranes prepared in this work consist of an ultra-microporous silica-based separative layer produced via a sol-gel process. Ultra microporous silica containing boron is synthesized by the acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate in ethanol. The layer is deposited inside a tubular asymmetric alumina support with a meso-porous y alumina inner layer. The thickness of the silica layers after treatment is about 200 nm, estimated from their cross-section SEM micrographs. Ultra-microporous membranes (with pore sizes less than 0.7 nm) are thus required to get high selectivity. Such membranes enable to carry out gas separation up to 500 deg C under a transmembrane pressure lower than 8 bars. He and H 2 permeance values close to 10 -7 mol.m -2 s -1 Pa -1 are obtained, associated with ideal selectivities α(He/CO 2 ) and α(H 2 /CO 2 ) between 10 and 20 at 300 deg C. (authors)

Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Kim, Ki-Seok [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of)

2011-11-30

Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: > For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. > Microporous carbons were formed by only carbonization without chemical activation. > The nitrogen content of microporous carbons was controlled by melamine content. > N-doped carbons showed higher specific capacitance compared to microporous carbons. > It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m{sup 2}/g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.

Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

International Nuclear Information System (INIS)

Kim, Ki-Seok; Park, Soo-Jin

2011-01-01

Graphical abstract: This describes the increase of specific capacitance in hybrid electrodes as a function of melamine content. Display Omitted Highlights: → For N-enriched hybrid carbons, co-precursors, PVDF/melamine composites, were used. → Microporous carbons were formed by only carbonization without chemical activation. → The nitrogen content of microporous carbons was controlled by melamine content. → N-doped carbons showed higher specific capacitance compared to microporous carbons. → It was attributed to the easy electron transfer and pseudocapacitance. - Abstract: Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m 2 /g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.

OXIDATIVE DEHYDROGENATION OF PROPANE BY RARE EARTH PHOSPHATES SUPPORTED ON AL-PILC

Directory of Open Access Journals (Sweden)

Carolina De Los Santos

2012-12-01

Full Text Available Catalytic activity in propane oxidative dehydrogenation of rare earth phosphates LnPO4 (where Ln = La, Ce, Pr, Nd, Sm and of the same supported by an aluminum pillared clay, of high specific surface area, is presented. The solids were characterized by TGA, XRD, nitrogen adsorption and immediate analysis after reaction in order to determine eventual carbon formation. Catalytic assays were performed at temperatures in the range 400oC-600oC, the reaction mixture was C3H8/O2/Ar = 10/10/80. All the catalysts were active. The reaction products were H2, CO, CO2, CH4, C2H4 and C3H6 and there were no organic oxygenated compounds detected. Although all the investigated systems were active, the Al-PILC supported catalysts presented a higher activity than the bulk materials. In this context, the samarium supported catalyst showed a propene yield increase from 4% to 10% compared with bulk samarium phosphate at 600°C. This effect was attributed to the increase in the specific surface area.

Microporous Silica Based Membranes for Desalination

Directory of Open Access Journals (Sweden)

João C. Diniz da Costa

2012-09-01

Full Text Available This review provides a global overview of microporous silica based membranes for desalination via pervaporation with a focus on membrane synthesis and processing, transport mechanisms and current state of the art membrane performance. Most importantly, the recent development and novel concepts for improving the hydro-stability and separating performance of silica membranes for desalination are critically examined. Research into silica based membranes for desalination has focussed on three primary methods for improving the hydro-stability. These include incorporating carbon templates into the microporous silica both as surfactants and hybrid organic-inorganic structures and incorporation of metal oxide nanoparticles into the silica matrix. The literature examined identified that only metal oxide silica membranes have demonstrated high salt rejections under a variety of feed concentrations, reasonable fluxes and unaltered performance over long-term operation. As this is an embryonic field of research several target areas for researchers were discussed including further improvement of the membrane materials, but also regarding the necessity of integrating waste or solar heat sources into the final process design to ensure cost competitiveness with conventional reverse osmosis processes.

Nanosized catalysts based on Fe oxide for combustion of n-hexane

International Nuclear Information System (INIS)

Picasso, Gino; Hermoza, Emilia; Lopez, Alcides; Gomez, Gemma; Pina, Maria Pilar; Herguido, Javier

2009-01-01

In this work, nanosized catalysts on Fe oxide have been prepared for total combustion on n-hexane (2000 ppmV). The synthesis of Fe oxide have been performed following sol-gel procedure starting from precursors based on nitrate salts. According to XRD analysis, nanoparticles formed α-hematite and the average particle size estimated by TEM was 9 nm with formation of agglomerations of 140 nm. Moreover, different clays pillared with Al (Al-PILC), Ti (Ti-PILC) and Fe (Fe-PILC) have been synthesized. Some samples based on Fe-Mn equimolar mixed supported on Al-PILC (FeMn/Al-PILC) and on Ti-PILC (FeMn/Ti-PILC) have been prepared in order to study the cooperative effect of Mn. Experimental conditions of calcination were adjusted in order to obtain samples with high thermal stability. XRD analysis of pillared samples revealed the formation of stable pillars, except for Fe-PILC which described a delaminated structure. As a consequence of pillaring, an enhancement of total surface area compared to starting clay material is observed. Concerning surface area, the decreasing order series of pillared material was: Ti-PILC > Fe-PILC > Al-PILC. Depression of total surface area decreasing of basal spacing d 001 with no modification of basal structure of starting natural clay have been observed due to the incorporation of Fe-Mn active phase into the structures of Ti-PILC and Al-PILC. The Fe-Mn mixed phase supported over pillared material exhibited higher catalytic activity than the Fe-PILC sample, which was attributed to the cooperative effect of Mn. This effect could be associated with redox properties of Mn and improving of surface oxygen mobility. Delaminated structure and strong interaction of Fe with clay porous network into the Fe-PILC sample could be the reason of lower activities. However, higher performances were observed in the case of Fe oxide nanoparticles prepared with surfactant agent over bentonite, due to a lesser extent of Fe-porous structure interaction presented in

Synthesis and characterization of a microporous 6FDA-polyimide made from a novel carbocyclic pseudo Tröger's base diamine: Effect of bicyclic bridge on gas transport properties

KAUST Repository

Abdulhamid, Mahmoud A.; Ma, Xiaohua; Miao, Xiaohe; Pinnau, Ingo

2017-01-01

,11-methanodibenzo[a,e][8]annulene (iCTBDA), were designed for the synthesis of microporous 6FDA-based polyimides (6FDA-CTBDA and 6FDA-iCTBDA). Both polyimides were soluble, exhibited excellent thermal stability of ∼490 °C, and had high surface areas of 587 m2 g−1 (6

Octyl Phenol Synthesis Using Natural Clays

Directory of Open Access Journals (Sweden)

S. Casuscelli

2000-03-01

Full Text Available A series of clay minerals, HB, NB and Al-PILC have been studied in the alkylation reactions of 2-octanol with phenol at 180°C, under conditions of alcohol/phenol = 1 (mole ratio and W/FAo °= 64,27 ghmol-1. The selectivity of Al-PILC was 77,12% for octyl phenol and 16,5% for dioctyl phenol.

Synthesis of N-rich microporous carbon materials from chitosan by alkali activation using Na{sub 2}CO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ilnicka, Anna; Lukaszewicz, Jerzy P., E-mail: jerzy_lukaszewicz@o2.pl

2015-11-15

Highlights: • The novel manufacturing procedure of nitrogen-rich carbon materials. • The biopolymer chitosan can be activated by sodium carbonate. • The effect of the addition of activator and the temperature of carbonization was investigated. • The N-rich carbon materials exhibit high specific surface area and microporous structure. - Abstract: The paper presents the first systematic study on the synthesis of nitrogen-rich nanoporous activated carbons by chitosan carbonization in the presence of a hard template (activator), i.e. Na{sub 2}CO{sub 3}. Carbonization process was carried out in the range of 600–900 °C under a flow of nitrogen. The effect of the addition of different volumes of activator and the temperature of carbonization on the development of specific surface area and pore structure (pore volume and median pore diameter) of the activated carbons was investigated. Additionally, the nitrogen content and nitrogen-containing surface species were determined by means of XPS and combustion elemental analysis. The nitrogen content was placed in the range of 2.4–13.1 wt.%. On the grounds of the low-temperature adsorption of nitrogen, it was found that obtained adsorption isotherms were of type-I, based on the IUPAC classification, which is typical for microporous materials.

Facile synthesis of microporous carbon through a soft-template pathway and its performance in desulfurization and denitrogenation

Institute of Scientific and Technical Information of China (English)

Bo Sun; Gang Li; Xiaoxing Wang

2010-01-01

Wormlike/lamellar microporous carbons were prepared by using long alkyl chain primary amine hydrochloride as the template and resorcinol/formaldehyde as the carbon source under highly acidic conditions. The template can be eliminated by high temperature treatment under an inert atmosphere. The obtained carbon materials were characterized by N2 adsorption-desorption, transmission electron microscopy, thermogravimetry and scanning electron microscopy. The results show that dodecylamine hydrochloride surfactant can be used as the template of wormlike micropores structure while octadecylamine hydrochloride results in both lamellar and wormlike micropores. The obtained carbon materials have the similar pore size in the range of 0.5～0.59 nm, but with various morphologies such as monolith, spheres, and coralline. The microporous carbon obtained from dodecytamine hydrochloride surfactant shows good "adsorption performance to remove the refractory sulfur compounds and nitrogen-containing compounds in fuel.

The influence of micropore size on the mechanical properties of bulk hydroxyapatite and hydroxyapatite scaffolds.

Science.gov (United States)

Cordell, Jacqueline M; Vogl, Michelle L; Wagoner Johnson, Amy J

2009-10-01

While recognized as a promising bone substitute material, hydroxyapatite (HA) has had limited use in clinical settings because of its inherent brittle behavior. It is well established that macropores ( approximately 100 microm) in a HA implant, or scaffold, are required for bone ingrowth, but recent research has shown that ingrowth is enhanced when scaffolds also contain microporosity. HA is sensitive to synthesis and processing parameters and therefore characterization for specific applications is necessary for transition to the clinic. To that end, the mechanical behavior of bulk microporous HA and HA scaffolds with multi-scale porosity (macropores between rods in the range of 250-350 microm and micropores within the rods with average size of either 5.96 microm or 16.2 microm) was investigated in order to determine how strength and reliability were affected by micropore size (5.96 microm versus 16.2 microm). For the bulk microporous HA, strength increased with decreasing micropore size in both bending (19 MPa to 22 MPa) and compression (71 MPa to 110 MPa). To determine strength reliability, the Weibull moduli for the bulk microporous HA were determined. The Weibull moduli for bending increased (became more reliable) with decreasing pore size (7 to 10) while the Weibull moduli for compression decreased (became less reliable) with decreasing pore size (9 to 6). Furthermore, the elastic properties of the bulk microporous HA (elastic modulus of 30 GPa) and the compressive strengths of the HA scaffolds with multi-scale porosity (8 MPa) did not vary with pore size. The mechanisms responsible for the trends observed were discussed.

Formation Mechanism of Micropores on the Surface of Pure Aluminum Induced by High-Current Pulsed Electron Beam Irradiation

International Nuclear Information System (INIS)

Zou Yang; Cai Jie; Wan Ming-Zhen; Lv Peng; Guan Qing-Feng

2011-01-01

The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained. It is discovered that dispersed micropores with sizes of 0.1–1 μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation. The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along grain boundaries and/or dislocations towards the irradiated surface. It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials. (condensed matter: structure, mechanical and thermal properties)

Response of MG63 osteoblast-like cells onto polycarbonate membrane surfaces with different micropore sizes.

Science.gov (United States)

Lee, Sang Jin; Choi, Jin San; Park, Ki Suk; Khang, Gilson; Lee, Young Moo; Lee, Hai Bang

2004-08-01

Response of different types of cells on materials is important for the applications of tissue engineering and regenerative medicine. It is recognized that the behavior of the cell adhesion, proliferation, and differentiation on materials depends largely on surface characteristics such as wettability, chemistry, charge, rigidity, and roughness. In this study, we examined the behavior of MG63 osteoblast-like cells cultured on a polycarbonate (PC) membrane surfaces with different micropore sizes (0.2-8.0 microm in diameter). Cell adhesion and proliferation to the PC membrane surfaces were determined by cell counting and MTT assay. The effect of surface micropore on the MG63 cells was evaluated by cell morphology, protein content, and alkaline phosphatase (ALP) specific activity. It seems that the cell adhesion and proliferation were progressively inhibited as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. Increasing micropore size of the PC membrane results in improved protein synthesis and ALP specific activity in isolated cells. There was a statistically significant difference (Pmicropore sizes. The MG63 cells also maintained their phenotype under conditions that support a round cell shape. RT-PCR analysis further confirmed the osteogenic phenotype of the MG63 cells onto the PC membranes with different micropore sizes. In results, as micropore size is getting larger, cell number is reduced and cell differentiation and matrix production is increased. This study demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells.

Study of zirconia microporous structure

International Nuclear Information System (INIS)

Gavrilov, V.Yu.

2000-01-01

Microporous structure of zirconium dioxide obtained by precipitation at variation of precipitating pH and time of gel aging was investigated with use of data on physical adsorption of nitrogen, oxygen and molecular hydrogen. Proportional increase of the supermicropore surface value measured on adsorption of O 2 over the value measured on adsorption of N 2 depending on the value of properly supermicropore detected earlier was shown to be held for zirconium dioxide. Formation of ZrO 2 microporous structure is precipitation pH dependent. Increase of pH on the 4 - 7 interval leads to decrease of volume of micropores during synchronous increase of supermicropore surface value, and mesopore at pH > 5. Gel aging is followed by additional reconstruction involving increase of sizes of micropores at minor increase of their common volume. Limit volume of sorption space of xerogel and common porosity grow take place too [ru

Microporous polystyrene particles for selective carbon dioxide capture.

Science.gov (United States)

Kaliva, Maria; Armatas, Gerasimos S; Vamvakaki, Maria

2012-02-07

This study presents the synthesis of microporous polystyrene particles and the potential use of these materials in CO(2) capture for biogas purification. Highly cross-linked polystyrene particles are synthesized by the emulsion copolymerization of styrene (St) and divinylbenzene (DVB) in water. The cross-link density of the polymer is varied by altering the St/DVB molar ratio. The size and the morphology of the particles are characterized by scanning and transmission electron microscopy. Following supercritical point drying with carbon dioxide or lyophilization from benzene, the polystyrene nanoparticles exhibit a significant surface area and permanent microporosity. The dried particles comprising 35 mol % St and 65 mol % DVB possess the largest surface area, ∼205 m(2)/g measured by Brunauer-Emmett-Teller and ∼185 m(2)/g measured by the Dubinin-Radushkevich method, and a total pore volume of 1.10 cm(3)/g. Low pressure measurements suggest that the microporous polystyrene particles exhibit a good separation performance of CO(2) over CH(4), with separation factors in the range of ∼7-13 (268 K, CO(2)/CH(4) = 5/95 gas mixture), which renders them attractive candidates for use in gas separation processes.

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores.

Science.gov (United States)

Cheng, Hefa; Reinhard, Martin

2010-07-15

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microporous solids and investigating contaminant-solid interactions. 2010 Elsevier B.V. All rights reserved.

Synthesis and Characterisation of Aluminophosphate Molecular Sieves

Energy Technology Data Exchange (ETDEWEB)

Halvorsen, E.N.

1996-02-01

Catalysts are very important in petrochemical processes. One of the properties that make crystalline, microporous materials attractive for catalytic purposes is their well-defined structure and ability to act as shape selective catalysts. This doctoral thesis presents the synthesis and characterization of a number of crystalline, microporous aluminophosphates and silicoaluminophosphates. 99 refs., 50 figs., 12 tabs.

Microporous glasses for pro-ecological applications

International Nuclear Information System (INIS)

Procyk, B.; Stoch, L.; Kubacki, M.; Rewilak, M.; Soltysiak, J.

1994-01-01

Microporous glasses are obtained by appropriate thermal and chemical treatment. On account of their sorptive properties microporous glasses represent an excellent material for storing high-energy radioactive waste products in nuclear power engineering and for binding toxins in natural environment. Microporous glasses may be used as membranes non-organic, as gel filling in chromatography. They may find application in biochemistry, chemical, metallurgical, electrochemical and other industries. The above applications depend on the internal arrangement, size and shape of pores. (author). 4 refs, 4 figs, 1 tab

Facile Synthesis of a Pentiptycene-Based Highly Microporous Organic Polymer for Gas Storage and Water Treatment.

Science.gov (United States)

Luo, Shuangjiang; Zhang, Qinnan; Zhang, Yizhou; Weaver, Kevin P; Phillip, William A; Guo, Ruilan

2018-05-02

Rigid H-shaped pentiptycene units, with an intrinsic hierarchical structure, were employed to fabricate a highly microporous organic polymer sorbent via Friedel-Crafts reaction/polymerization. The obtained microporous polymer exhibits good thermal stability, a high Brunauer-Emmett-Teller surface area of 1604 m 2 g -1 , outstanding CO 2 , H 2 , and CH 4 storage capacities, as well as good adsorption selectivities for the separation of CO 2 /N 2 and CO 2 /CH 4 gas pairs. The CO 2 uptake values reached as high as 5.00 mmol g -1 (1.0 bar and 273 K), which, along with high adsorption selectivity values (e.g., 47.1 for CO 2 /N 2 ), make the pentiptycene-based microporous organic polymer (PMOP) a promising sorbent material for carbon capture from flue gas and natural gas purification. Moreover, the PMOP material displayed superior absorption capacities for organic solvents and dyes. For example, the maximum adsorption capacities for methylene blue and Congo red were 394 and 932 mg g -1 , respectively, promoting the potential of the PMOP as an excellent sorbent for environmental remediation and water treatment.

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores

Energy Technology Data Exchange (ETDEWEB)

Cheng Hefa [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Reinhard, Martin, E-mail: reinhard@stanford.edu [Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020 (United States)

2010-07-15

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microprous solids and investigating contaminant-solid interactions.

In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores

International Nuclear Information System (INIS)

Cheng Hefa; Reinhard, Martin

2010-01-01

Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microprous solids and investigating contaminant-solid interactions.

Panels of microporous insulation

Energy Technology Data Exchange (ETDEWEB)

McWilliams, J.A.; Morgan, D.E.; Jackson, J.D.J.

1990-08-07

Microporous thermal insulation materials have a lattice structure in which the average interstitial dimension is less than the mean free path of the molecules of air or other gas in which the material is arranged. This results in a heat flow which is less than that attributable to the molecular heat diffusion of the gas. According to this invention, a method is provided for manufacturing panels of microporous thermal insulation, in particular such panels in which the insulation material is bonded to a substrate. The method comprises the steps of applying a film of polyvinyl acetate emulsion to a non-porous substrate, and compacting powdery microporous thermal insulation material against the film so as to cause the consolidated insulation material to bond to the substrate and form a panel. The polyvinyl acetate may be applied by brushing or spraying, and is preferably allowed to dry prior to compacting the insulation material. 1 fig.

Nitrogen-doped micropore-dominant carbon derived from waste pine cone as a promising metal-free electrocatalyst for aqueous zinc/air batteries

Science.gov (United States)

Lei, Xiaoke; Wang, Mengran; Lai, Yanqing; Hu, Langtao; Wang, Hao; Fang, Zhao; Li, Jie; Fang, Jing

2017-10-01

The exploitation for highly effective and low-cost metal-free catalysts with facile and environmental friendly method for oxygen reduction reaction is still a great challenge. To find an effective method for catalyst synthesis, in this manuscript, waste biomass pine cone is employed as raw material and nitrogen-doped micropore-dominant carbon material with excellent ORR catalytic activity is successfully synthesized. The as-prepared N-doped micropore-dominant carbon possesses a high surface area of 1556 m2 g-1. In addition, this carbon electrocatalyst loaded electrode exhibits a high discharge voltage 1.07 V at the current density of 50 mA cm-2, which can be ascribed to the rich micropores and high content of pyridinic N of the prepared carbon, indicative of great potential in the application of zinc/air batteries.

Covalent organic framework-derived microporous carbon nanoparticles coated with conducting polypyrrole as an electrochemical capacitor

Science.gov (United States)

Kim, Dong Jun; Yoon, Jung Woon; Lee, Chang Soo; Bae, Youn-Sang; Kim, Jong Hak

2018-05-01

We report a high-performance electrochemical capacitor based on covalent organic framework (COF)-derived microporous carbon (MPC) nanoparticles and electrochemically polymerized polypyrrole (Ppy) as a pseudocapacitive material. The COF, Schiff-based network-1 (SNW-1) nanoparticles are prepared via a condensation reaction between melamine and terephthalaldehyde, and the resultant MPC film is prepared via a screen-printing method. The MPC film exhibits a bimodal porous structure with micropores and macropores, resulting in both a large surface area and good electrolyte infiltration. Ppy is synthesized potentio-statically (0.8 V vs. Ag/AgCl) by varying the reaction time, and successful synthesis of Ppy is confirmed via Raman spectroscopy. The specific capacitance with the Ppy coating is enhanced by up to 2.55 F cm-2 due to the synergetic effect of pseudocapacitance and reduced resistance.

A study on ion microporous membrane and its application

International Nuclear Information System (INIS)

Guo Hongying; Huang Zhengde

2002-01-01

The author depicted the physical, chemical character and the applied fields of ion microporous membrane. The technological procedure of making ion microporous membrane, applications in microporous counter-feinting trademark by heavy ion imaging and medical filtrater in authors' institute were stated

Measuring hydrophobic micropore volumes in geosorbents from trichloroethylene desorption data.

Science.gov (United States)

Cheng, Hefa; Reinhard, Martin

2006-06-01

Hydrophobic micropores can play a significant role in controlling the long-term release of organic contaminants from geosorbents. We describe a technique for quantifying the total and the hydrophobic mineral micropore volumes based on the mass of trichloroethylene (TCE) sorbed in the slow-releasing pores under dry and wet conditions, respectively. Micropore desorption models were used to differentiate the fast- and slow-desorbing fractions in desorption profiles. The micropore environment in which organic molecules were sorbed in the presence of water was probed by studying the transformation of a water-reactive compound (2,2-dichloropropane or 2,2-DCP). For sediment from an alluvial aquifer, the total and hydrophobic micropore volumes estimated using this technique were 4.65 microL/g and 0.027 microL/g (0.58% of total), respectively. In microporous silica gel A, a hydrophobic micropore volume of 0.038 microL/g (0.035% of reported total) was measured. The dehydrohalogenation rate of 2,2-DCP sorbed in hydrophobic micropores of the sediment was slower than that reported in bulk water, indicating an environment of low water activity. The results suggest that hydrolyzable organic contaminants sorbed in hydrophobic micropores react slower than in bulk water, consistent with the reported persistence of reactive contaminants in natural soils.

Micropores and methods of making and using thereof

Science.gov (United States)

Perroud, Thomas D.; Patel, Kamlesh D.; Meagher, Robert J.

2016-08-02

Disclosed herein are methods of making micropores of a desired height and/or width between two isotropic wet etched features in a substrate which comprises single-level isotropic wet etching the two features using an etchant and a mask distance that is less than 2.times. a set etch depth. Also disclosed herein are methods using the micropores and microfluidic devices comprising the micropores.

Improved Fibroblast Functionalities by Microporous Pattern Fabricated by Microelectromechanical Systems

Science.gov (United States)

Wei, Hongbo; Zhao, Lingzhou; Chen, Bangdao; Bai, Shizhu; Zhao, Yimin

2014-01-01

Fibroblasts, which play an important role in biological seal formation and maintenance, determine the long-term success of percutaneous implants. In this study, well-defined microporous structures with micropore diameters of 10–60 µm were fabricated by microelectromechanical systems and their influence on the fibroblast functionalities was observed. The results show that the microporous structures with micropore diameters of 10–60 µm did not influence the initial adherent fibroblast number; however, those with diameters of 40 and 50 µm improved the spread, actin stress fiber organization, proliferation and fibronectin secretion of the fibroblasts. The microporous structures with micropore diameters of 40–50 µm may be promising for application in the percutaneous part of an implant. PMID:25054322

Improved Fibroblast Functionalities by Microporous Pattern Fabricated by Microelectromechanical Systems

Directory of Open Access Journals (Sweden)

Hongbo Wei

2014-07-01

Full Text Available Fibroblasts, which play an important role in biological seal formation and maintenance, determine the long-term success of percutaneous implants. In this study, well-defined microporous structures with micropore diameters of 10–60 µm were fabricated by microelectromechanical systems and their influence on the fibroblast functionalities was observed. The results show that the microporous structures with micropore diameters of 10–60 µm did not influence the initial adherent fibroblast number; however, those with diameters of 40 and 50 µm improved the spread, actin stress fiber organization, proliferation and fibronectin secretion of the fibroblasts. The microporous structures with micropore diameters of 40–50 µm may be promising for application in the percutaneous part of an implant.

Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

Science.gov (United States)

Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

2015-01-01

The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85 wt % ethanol aqueous solution at 45 °C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and effect of physical aging on gas transport properties of a microporous polyimide derived from a novel spirobifluorene-based dianhydride

KAUST Repository

Ma, Xiaohua; Ghanem, Bader; Salinas, Octavio; Litwiller, Eric; Pinnau, Ingo

2015-01-01

A novel generic method is reported for the synthesis of a spirobifluorene-based dianhydride (SBFDA). An intrinsically microporous polyimide was obtained by polycondensation reaction with 3,3′-dimethylnaphthidine (DMN). The corresponding polymer (SBFDA-DMN) exhibited good solubility, excellent thermal stability, as well as significant microporosity with high BET surface area of 686 m2/g. The O2 permeability of a methanol-treated and air-dried membrane was 1193 Barrer with a moderate O2/N2 selectivity of 3.2. The post-treatment history and aging conditions had great effects on the membrane performance. A significant drop in permeability coupled with an increase in selectivity was observed after long-term aging. After storage of 200 days, the gas separation properties of SBFDA-DMN were located slightly above the latest Robeson upper bounds for several gas pairs such as O2/N2 and H2/N2.

Synthesis and effect of physical aging on gas transport properties of a microporous polyimide derived from a novel spirobifluorene-based dianhydride

KAUST Repository

Ma, Xiaohua

2015-02-17

A novel generic method is reported for the synthesis of a spirobifluorene-based dianhydride (SBFDA). An intrinsically microporous polyimide was obtained by polycondensation reaction with 3,3′-dimethylnaphthidine (DMN). The corresponding polymer (SBFDA-DMN) exhibited good solubility, excellent thermal stability, as well as significant microporosity with high BET surface area of 686 m2/g. The O2 permeability of a methanol-treated and air-dried membrane was 1193 Barrer with a moderate O2/N2 selectivity of 3.2. The post-treatment history and aging conditions had great effects on the membrane performance. A significant drop in permeability coupled with an increase in selectivity was observed after long-term aging. After storage of 200 days, the gas separation properties of SBFDA-DMN were located slightly above the latest Robeson upper bounds for several gas pairs such as O2/N2 and H2/N2.

Synthesis of metalloporphyrin-based conjugated microporous polymer spheres directed by bipyridine-type ligands.

Science.gov (United States)

Ji, Guipeng; Yang, Zhenzhen; Zhao, Yanfei; Zhang, Hongye; Yu, Bo; Xu, Jilei; Xu, Huanjun; Liu, Zhimin

2015-04-30

Zinc porphyrin (TP-Zn)-based conjugated microporous polymer (Zn-CMP) spheres were obtained via Sonagashira-Hagihara cross coupling reactions between 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin-Zn(II) and brominated monomers directed by bidentate bipyridine (BP)-type ligands for the first time, and the sphere diameters could be adjusted from 320 to 740 nm. The coordination between BP and TP-Zn was proved to be the key to forming spheres.

Facile synthesis of triazine-triphenylamine-based microporous covalent polymer adsorbent for flue gas CO2 capture

KAUST Repository

Das, Swapan Kumar; Wang, Xinbo; Lai, Zhiping

2017-01-01

The sustainable capture and sequestration of CO2 from flue gas emission is an important and unavoidable challenge to control greenhouse gas release and climate change. In this report, we describe a triazine-triphenylamine-based microporous covalent

Amorphous ice. A microporous solid: astrophysical implications

International Nuclear Information System (INIS)

Mayer, E.; Pletzer, R.

1987-01-01

Vapour deposited amorphous ice, investigated by N 2 -adsorption at 77 K, was found to be a microporous solid. Micropore volumes between 0.21 and 0.12 cm 3 /g were determined by comparison plots and Dubinin-Radushkevich plots. Warming of the adsorbent to 113 K caused sintering and reduction of apparent surface area by about an order of magnitude; in the presence of adsorbed gas, large amounts of gas were enclosed in the solid. The influence of micropores on the H 2 recombination rate on amorphous ice in interstellar dust and on adsorption of volatile gases in comets is discussed briefly

Improved Fibroblast Functionalities by Microporous Pattern Fabricated by Microelectromechanical Systems

OpenAIRE

Wei, Hongbo; Zhao, Lingzhou; Chen, Bangdao; Bai, Shizhu; Zhao, Yimin

2014-01-01

Fibroblasts, which play an important role in biological seal formation and maintenance, determine the long-term success of percutaneous implants. In this study, well-defined microporous structures with micropore diameters of 10–60 µm were fabricated by microelectromechanical systems and their influence on the fibroblast functionalities was observed. The results show that the microporous structures with micropore diameters of 10–60 µm did not influence the initial adherent fibroblast number; ...

Numerical simulation of fluid flow in microporous media

International Nuclear Information System (INIS)

Xu Ruina; Jiang Peixue

2008-01-01

The flow characteristics of water and air in microporous media with average diameters of 200 μm, 125 μm, 90 μm, 40 μm, 20 μm, and 10 μm were studied numerically. The calculated friction factors for water and air in the non-slip-flow regime in the microporous media agree well with the known correlation suitable for normal size porous media. The numerically predicted friction factors for air in the slip-flow regime in the microporous media with 90 μm, 40 μm, 20 μm, and 10 μm diameter particles were less than the correlation for normal size porous media but close to experimental data and a modified correlation that accounts for rarefaction. Comparisons of the numerical results with the experimental data and the modified correlations show that rarefaction effects occur in air flows in the microporous media with particle diameters less than 90 μm and that the numerical calculations with velocity slip on the boundary can properly simulate the fluid flow in microporous media

Cyclic Di-GMP Binding by an Assembly ATPase (PilB2) and Control of Type IV Pilin Polymerization in the Gram-Positive Pathogen Clostridium perfringens.

Science.gov (United States)

Hendrick, William A; Orr, Mona W; Murray, Samantha R; Lee, Vincent T; Melville, Stephen B

2017-05-15

polymerizing the pilin, PilA2, into a pilus. The assembly ATPase PilB2 and its cognate membrane protein partner, PilC2, were purified. PilB2 bound the intracellular signal molecule c-di-GMP. Increased levels of intracellular c-di-GMP led to increased polymerization of PilA2, indicating that Gram-positive bacteria use this molecule to regulate pilus synthesis. These findings provide valuable information for understanding how pathogenic clostridia regulate TFP to cause human diseases. Copyright © 2017 American Society for Microbiology.

Selective individual primary cell capture using locally bio-functionalized micropores.

Directory of Open Access Journals (Sweden)

Jie Liu

Full Text Available BACKGROUND: Solid-state micropores have been widely employed for 6 decades to recognize and size flowing unlabeled cells. However, the resistive-pulse technique presents limitations when the cells to be differentiated have overlapping dimension ranges such as B and T lymphocytes. An alternative approach would be to specifically capture cells by solid-state micropores. Here, the inner wall of 15-µm pores made in 10 µm-thick silicon membranes was covered with antibodies specific to cell surface proteins of B or T lymphocytes. The selective trapping of individual unlabeled cells in a bio-functionalized micropore makes them recognizable just using optical microscopy. METHODOLOGY/PRINCIPAL FINDINGS: We locally deposited oligodeoxynucleotide (ODN and ODN-conjugated antibody probes on the inner wall of the micropores by forming thin films of polypyrrole-ODN copolymers using contactless electro-functionalization. The trapping capabilities of the bio-functionalized micropores were validated using optical microscopy and the resistive-pulse technique by selectively capturing polystyrene microbeads coated with complementary ODN. B or T lymphocytes from a mouse splenocyte suspension were specifically immobilized on micropore walls functionalized with complementary ODN-conjugated antibodies targeting cell surface proteins. CONCLUSIONS/SIGNIFICANCE: The results showed that locally bio-functionalized micropores can isolate target cells from a suspension during their translocation throughout the pore, including among cells of similar dimensions in complex mixtures.

Selective Individual Primary Cell Capture Using Locally Bio-Functionalized Micropores

Science.gov (United States)

Liu, Jie; Bombera, Radoslaw; Leroy, Loïc; Roupioz, Yoann; Baganizi, Dieudonné R.; Marche, Patrice N.; Haguet, Vincent; Mailley, Pascal; Livache, Thierry

2013-01-01

Background Solid-state micropores have been widely employed for 6 decades to recognize and size flowing unlabeled cells. However, the resistive-pulse technique presents limitations when the cells to be differentiated have overlapping dimension ranges such as B and T lymphocytes. An alternative approach would be to specifically capture cells by solid-state micropores. Here, the inner wall of 15-µm pores made in 10 µm-thick silicon membranes was covered with antibodies specific to cell surface proteins of B or T lymphocytes. The selective trapping of individual unlabeled cells in a bio-functionalized micropore makes them recognizable just using optical microscopy. Methodology/Principal Findings We locally deposited oligodeoxynucleotide (ODN) and ODN-conjugated antibody probes on the inner wall of the micropores by forming thin films of polypyrrole-ODN copolymers using contactless electro-functionalization. The trapping capabilities of the bio-functionalized micropores were validated using optical microscopy and the resistive-pulse technique by selectively capturing polystyrene microbeads coated with complementary ODN. B or T lymphocytes from a mouse splenocyte suspension were specifically immobilized on micropore walls functionalized with complementary ODN-conjugated antibodies targeting cell surface proteins. Conclusions/Significance The results showed that locally bio-functionalized micropores can isolate target cells from a suspension during their translocation throughout the pore, including among cells of similar dimensions in complex mixtures. PMID:23469221

Manufacturing microporous membrane by polymerisation

International Nuclear Information System (INIS)

Tanny, G.B.

1984-01-01

The starting materials for the practice of the present invention are (1) one or more organic monomers or oligomers which upon irradiation very rapidly undergo a polymerization reaction to form a solid polymer; and (2) a liquid vehicle in which the one or more organic monomers or oligomers are soluble but in which the polymer formed is insoluble. For the manufacture of microporous membrane in accordance with the invention the monomers or oligomers are dissolved in the liquid vehicle, the resulting solution is formed into a thin layer, and the thin layer of the solution is then irradiated as with ultraviolet or electron beam radiation whereupon the rapid polymerization reaction immediately ensues and the polymer formed immediately segregates from the vehicle thereby resulting in microporous membrane from which the vehicle can be removed as by evaporation or washing. Because the radiation-induced polymerization reaction and the segregation of the polymer formed are so rapid, the membrane formed has cells and communications therebetween of very small dimensions thereby providing the microporous structure. Where ultra-violet radiation is used the solution also includes a photo-initiator. (author)

Diclofenac delays micropore closure following microneedle treatment in human subjects

Science.gov (United States)

Brogden, Nicole K.; Milewski, Mikolaj; Ghosh, Priyanka; Hardi, Lucia; Crofford, Leslie J.; Stinchcomb, Audra L.

2013-01-01

Drugs absorbed poorly through the skin are commonly delivered via injection with a hypodermic needle, which is painful and increases the risk of transmitting infectious diseases. Microneedles (MNs) selectively and painlessly permeabilize the outermost skin layer, allowing otherwise skin-impermeable drugs to cross the skin through micron-sized pores and reach therapeutic concentrations. However, rapid healing of the micropores prevents further drug delivery, blunting the clinical utility of this unique transdermal technique. We present the first human study demonstrating that micropore lifetime can be extended following MN treatment. Subjects received one-time MN treatment and daily topical application of diclofenac sodium. Micropore closure was measured with impedance spectroscopy, and area under the admittance–time curve (AUC) was calculated. AUC was significantly higher at MN + diclofenac sodium sites vs. placebo, suggesting slower rates of micropore healing. Colorimetry measurements confirmed the absence of local erythema and irritation. This mechanistic human proof-of-concept study demonstrates that micropore lifetime can be prolonged with simple topical administration of a non-specific cyclooxygenase inhibitor, suggesting the involvement of subclinical inflammation in micropore healing. These results will allow for longer patch wear time with MN-enhanced delivery, thus increasing patient compliance and expanding the transdermal field to a wider variety of clinical conditions. PMID:22929967

Morphology design of microporous organic polymers and their potential applications: an overview

Institute of Scientific and Technical Information of China (English)

Qingyin Li; Shumaila Razzaque; Shangbin Jin; Bien Tan

2017-01-01

Microporous organic polymers (MOPs) have attracted considerable research interest because of their well-defined porosity,high surface area,lightweight nature,and tunable surface chemistry.The morphology of MOPs are demonstrated to play a significant role in various applications although limited examples manifesting the importance of the MOP morphology in numerous applications have been reported.This review summarizes the recent progress in the design of MOPs using different techniques,including hard and soft template and direct synthesis methods.In addition,their applications,which possibly attribute to their shape,are discussed.Furthermore,the advantages and disadvantages of different methods are discussed,as well as their development and future challenges.

Attractive forces in microporous carbon electrodes for capacitive deionization

NARCIS (Netherlands)

Biesheuvel, P.M.; Porada, S.; Levi, M.; Bazant, M.Z.

2014-01-01

The recently developed modified Donnan (mD) model provides a simple and useful description of the electrical double layer in microporous carbon electrodes, suitable for incorporation in porous electrode theory. By postulating an attractive excess chemical potential for each ion in the micropores

Microporous polyurethane-acrylamide film cured by electron beam irradiation

International Nuclear Information System (INIS)

Ando, Masayuki; Goto, Takakazu; Tsuchiya, Mitsuru; Uryu, Toshiyuki

1988-01-01

The morphology and aggregation structure of electron beam (EB)-cured microporous polyurethane-acrylamide film was investigated. The urethane-acrylamide prepolymer was synthesized by the reaction of poly(butylene adipate)diol, diphenylmethane diisocyanate, and N-(hydroxymethyl)acrylamide. It was found from scanning electron microscopy that the urethane-acrylamide film, which was prepared by using a methyl ethyl ketone and dimethylformamide (3:1 v/v) mixture as casting solvent, had a microporous structure with pore size of several micrometers, and that the morphology was fixed by EB irradiation. The pore volume of the EB-cured microporous film was determined to be about 460 mm 3 g -1 by mercury porosimetry. The micropores were not destroyed even after immersing in solvent, possibly because the cured film had high crystallinity and dense crosslinking. Moreover, it was found by X-ray photelectron spectroscopy that terminal portions of urethane-acrylamide were localized at the film surface. (author)

Characterization of the microporous HDPE film with alpha alumina

International Nuclear Information System (INIS)

Park, Jong Seok; Sung, Hae Jun; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang

2010-01-01

The effects of the addition of the alpha alumina on the properties of the microporous high density polyethylene (HDPE) films were investigated. The particle size and the specific surface area of alpha alumina were 400 nm and 7.3 m 2 g -1 . The HDPE and the alpha alumina were mixed to obtain the precursor film in the twin extruder. The precursor films were uni-axially stretched up to 600% in oven 120 .deg. C and then the stretched HDPE films were irradiated by gamma rays. The pore volume of the microporous HDPE films was increased with an increasing content of the alpha alumina. The mechanical characteristics of the microporous HDPE films were increased with a content of alpha alumina up to 15%, but decreased at 20%. The electrochemical stability of the microporous HDPE film containing alpha alumia was increased with an increased irradiation dose up ti 50 kGy

The state of physically adsorbed substances in microporous adsorbents

International Nuclear Information System (INIS)

Fomkin, A.A.

1987-01-01

Xe, Kr, Ar, CF 3 Cl, CH 4 adsorption in NaX microporous zeolite of 0.98 Na 2 OxAl 2 O 3 x2.36SiO 2 x0.02H 2 O is studied. Some properties of adsorbates (density, coefficients of expansion, enthalpy, heat capacity) are determined and discussed. The adsorbate in the microporous adsorbent is shown to be a particular state of a substance. Liniarity of adsorption isosteres and sharp changes during isosteric heat capacity of the adsorbate points to the fact that in microporous adsorbents phase transformations of the second type are possible

The cost-effective synthesis of furan- and thienyl-based microporous polyaminals for adsorption of gases and organic vapors.

Science.gov (United States)

Li, Guiyang; Zhang, Biao; Yan, Jun; Wang, Zhonggang

2016-01-21

This work reveals that furfural and 2-thenaldehyde can readily react with melamine via "one-step" polycondensation to yield hyper-cross-linked sulfur-, nitrogen- and oxygen-rich microporous polyaminals with promising applications in adsorption of gases and toxic organic vapors.

Diclofenac delays micropore closure following microneedle treatment in human subjects.

Science.gov (United States)

Brogden, Nicole K; Milewski, Mikolaj; Ghosh, Priyanka; Hardi, Lucia; Crofford, Leslie J; Stinchcomb, Audra L

2012-10-28

Drugs absorbed poorly through the skin are commonly delivered via injection with a hypodermic needle, which is painful and increases the risk of transmitting infectious diseases. Microneedles (MNs) selectively and painlessly permeabilize the outermost skin layer, allowing otherwise skin-impermeable drugs to cross the skin through micron-sized pores and reach therapeutic concentrations. However, rapid healing of the micropores prevents further drug delivery, blunting the clinical utility of this unique transdermal technique. We present the first human study demonstrating that micropore lifetime can be extended following MN treatment. Subjects received one-time MN treatment and daily topical application of diclofenac sodium. Micropore closure was measured with impedance spectroscopy, and area under the admittance-time curve (AUC) was calculated. AUC was significantly higher at MN+diclofenac sodium sites vs. placebo, suggesting slower rates of micropore healing. Colorimetry measurements confirmed the absence of local erythema and irritation. This mechanistic human proof-of-concept study demonstrates that micropore lifetime can be prolonged with simple topical administration of a non-specific cyclooxygenase inhibitor, suggesting the involvement of subclinical inflammation in micropore healing. These results will allow for longer patch wear time with MN-enhanced delivery, thus increasing patient compliance and expanding the transdermal field to a wider variety of clinical conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui

2018-01-16

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

Science.gov (United States)

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional–ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent–induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson–Boltzmann equation

International Nuclear Information System (INIS)

Kitazumi, Yuki; Shirai, Osamu; Yamamoto, Masahiro; Kano, Kenji

2013-01-01

Graphical abstract: - Highlights: • Diffuse double layers overlap with each other in the micropore. • The overlapping of the diffuse double layer affects the double layer capacitance. • The electric field becomes weak in the micropore. • The electroneutrality is unsatisfactory in the micropore. - Abstract: The structure of the diffuse double layer around a nm-sized micropore on porous electrodes has been studied by numerical simulation using the Poisson–Boltzmann equation. The double layer capacitance of the microporous electrode strongly depends on the electrode potential, the electrolyte concentration, and the size of the micropore. The potential and the electrolyte concentration dependence of the capacitance is different from that of the planner electrode based on the Gouy's theory. The overlapping of the diffuse double layer becomes conspicuous in the micropore. The overlapped diffuse double layer provides the mild electric field. The intensified electric field exists at the rim of the orifice of the micropore because of the expansion of the diffuse double layers. The characteristic features of microporous electrodes are caused by the heterogeneity of the electric field around the micropores

Preparation of micro-pored silicone elastomer through radiation crosslinking

International Nuclear Information System (INIS)

Gao Xiaoling; Gu Mei; Xie Xubing; Huang Wei

2013-01-01

The radiation crosslinking was adopted to prepare the micro-pored silicone elastomer, which was performed by vulcanization and foaming respectively. Radiation crosslinking is a new method to prepare micro-pored material with high performance by use of radiation technology. Silicon dioxide was used as filler, and silicone elastomer was vulcanized by electron beams, then the micro-pored material was made by heating method at a high temperature. The effects of absorbed dose and filler content on the performance and morphology were investigated. The structure and distribution of pores were observed by SEM. The results show that the micro-pored silicon elastomer can be prepared successfully by controlling the absorbed dose and filler content. It has a smooth surface similar to a rubber meanwhile the pores are round and unconnected to each other with the minimum size of 14 μm. And the good mechanical performance can be suitable for further uses. (authors)

Toward Increasing Micropore Volume between Hybrid Layered Perovskites with Silsesquioxane Interlayers.

Science.gov (United States)

Kataoka, Sho; Kamimura, Yoshihiro; Endo, Akira

2018-04-10

Hybrid organic-inorganic layered perovskites are typically nonporous solids. However, the incorporation of silsesquioxanes with a cubic cage structure as interlayer materials creates micropores between the perovskite layers. In this study, we increase in the micropore volume in layered perovskites by replacing a portion of the silsesquioxane interlayers with organic amines. In the proposed method, approximately 20% of the silsesquioxane interlayers can be replaced without changing the layer distance owing to the size of the silsesquioxane. When small amines (e.g., ethylamine) are used in this manner, the micropore volume of the obtained hybrid layered perovskites increases by as much as 44%; when large amines (e.g., phenethylamine) are used, their micropore volume decreases by as much as 43%. Through the variation of amine fraction, the micropore volume can be adjusted in the range. Finally, the magnetic moment measurements reveal that the layered perovskites with mixed interlayers exhibit ferromagnetic ordering at temperature below 20 K, thus indicating that the obtained perovskites maintain their functions as layered perovskites.

Synthesis of N-doped microporous carbon via chemical activation of polyindole-modified graphene oxide sheets for selective carbon dioxide adsorption

International Nuclear Information System (INIS)

Saleh, Muhammad; Chandra, Vimlesh; Christian Kemp, K; Kim, Kwang S

2013-01-01

A polyindole-reduced graphene oxide (PIG) hybrid was synthesized by reducing graphene oxide sheets in the presence of polyindole. We have shown PIG as a material for capturing carbon dioxide (CO 2 ). The PIG hybrid was chemically activated at temperatures of 400–800 ° C, which resulted in nitrogen (N)-doped graphene sheets. The N-doped graphene sheets are microporous with an adsorption pore size of 0.6 nm for CO 2 and show a maximum (Brunauer, Emmet and Teller) surface area of 936 m 2 g −1 . The hybrid activated at 600 ° C (PIG6) possesses a surface area of 534 m 2 g −1 and a micropore volume of 0.29 cm 3 g −1 . PIG6 shows a maximum CO 2 adsorption capacity of 3.0 mmol g −1 at 25 ° C and 1 atm. This high CO 2 uptake is due to the highly microporous character of the material and its N content. The material retains its original adsorption capacity on recycling even after 10 cycles (within experimental error). PIG6 also shows high adsorption selectivity ratios for CO 2 over N 2 , CH 4 and H 2 of 23, 4 and 85 at 25 ° C, respectively. (paper)

Isotropically etched radial micropore for cell concentration, immobilization, and picodroplet generation.

Science.gov (United States)

Perroud, Thomas D; Meagher, Robert J; Kanouff, Michael P; Renzi, Ronald F; Wu, Meiye; Singh, Anup K; Patel, Kamlesh D

2009-02-21

To enable several on-chip cell handling operations in a fused-silica substrate, small shallow micropores are radially embedded in larger deeper microchannels using an adaptation of single-level isotropic wet etching. By varying the distance between features on the photolithographic mask (mask distance), we can precisely control the overlap between two etch fronts and create a zero-thickness semi-elliptical micropore (e.g. 20 microm wide, 6 microm deep). Geometrical models derived from a hemispherical etch front show that micropore width and depth can be expressed as a function of mask distance and etch depth. These models are experimentally validated at different etch depths (25.03 and 29.78 microm) and for different configurations (point-to-point and point-to-edge). Good reproducibility confirms the validity of this approach to fabricate micropores with a desired size. To illustrate the wide range of cell handling operations enabled by micropores, we present three on-chip functionalities: continuous-flow particle concentration, immobilization of single cells, and picoliter droplet generation. (1) Using pressure differentials, particles are concentrated by removing the carrier fluid successively through a series of 44 shunts terminated by 31 microm wide, 5 microm deep micropores. Theoretical values for the concentration factor determined by a flow circuit model in conjunction with finite volume modeling are experimentally validated. (2) Flowing macrophages are individually trapped in 20 microm wide, 6 microm deep micropores by hydrodynamic confinement. The translocation of transcription factor NF-kappaB into the nucleus upon lipopolysaccharide stimulation is imaged by fluorescence microscopy. (3) Picoliter-sized droplets are generated at a 20 microm wide, 7 microm deep micropore T-junction in an oil stream for the encapsulation of individual E. coli bacteria cells.

Synthesis and crystal structures of a novel layered silicate SSA-1 and its microporous derivatives by topotactic transformation.

Science.gov (United States)

Takahashi, S; Kurita, Y; Ikeda, T; Miyamoto, M; Uemiya, S; Oumi, Y

2016-10-18

The synthesis of a novel layered silicate SSA-1 (SSA: silicate synthesized with a quaternary amine) was achieved in the SiO 2 -H 2 O-TEAOH (TEAOH: tetraethylammonium hydroxide - as an organic structural directing agent) system. The crystal structure of SSA-1 involved two silicate layers composed of bre [10T]-type CBU (Composite Building Unit) and TEAOH in interlayers. The topotactic transformation of SSA-1 by calcination was examined, resulting in a porous material (PML-1: porous material transformed from a layered silicate) with a 108 m 2 g -1 BET surface area and 0.035 cm 3 g -1 pore volume. PML-1 is a siliceous microporous material with silanols in the framework and possesses unique properties, such as hydrophilicity, in spite of all its silica composition. The most reasonable crystal structure of PML-1 was successfully determined on the basis of the crystal structure of SSA-1 by a combination of manual modelling, PXRD pattern simulation, DFT optimization and Rietveld analysis. Additionally, an interlayer expanded siliceous zeolite SSA-1 (IEZ-SSA-1) was also successfully prepared by silylation using trichloro(methyl)silane under acidic conditions. IEZ-SSA-1 showed hydrophilicity or hydrophobicity properties by changing the functional group of the pillar part in the interlayer. Additionally, IEZ-SSA-1 showed a large gas adsorption property (537 m 2 g -1 and 0.21 cm 3 g -1 ).

Electrochemically induced maskless metal deposition on micropore wall.

Science.gov (United States)

Liu, Jie; Hébert, Clément; Pham, Pascale; Sauter-Starace, Fabien; Haguet, Vincent; Livache, Thierry; Mailley, Pascal

2012-05-07

By applying an external electric field across a micropore via an electrolyte, metal ions in the electrolyte can be reduced locally onto the inner wall of the micropore, which was fabricated in a silica-covered silicon membrane. This maskless metal deposition on the silica surface is a result of the pore membrane polarization in the electric field. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triazine containing N-rich microporous organic polymers for CO2 capture and unprecedented CO2/N2 selectivity

International Nuclear Information System (INIS)

Bhunia, Subhajit; Bhanja, Piyali; Das, Sabuj Kanti; Sen, Tapas; Bhaumik, Asim

2017-01-01

Targeted synthesis of microporous adsorbents for CO 2 capture and storage is very challenging in the context of remediation from green house gases. Herein we report two novel N-rich microporous networks SB-TRZ-CRZ and SB-TRZ-TPA by extensive incorporation of triazine containing tripodal moiety in the porous polymer framework. These materials showed excellent CO 2 storage capacities: SB-TRZ-CRZ displayed the CO 2 uptake capacity of 25.5 wt% upto 1 bar at 273 K and SB-TRZ-TPA gave that of 16 wt% under identical conditions. The substantial dipole quadruple interaction between network (polar triazine) and CO 2 boosts the selectivity for CO 2 /N 2 . SB-TRZ-CRZ has this CO 2 /N 2 selectivity ratio of 377, whereas for SB-TRZ-TPA it was 97. Compared to other porous polymers, these materials are very cost effective, scalable and very promising material for clean energy application and environmental issues. - Graphical abstract: We report two novel N-rich microporous polymeric materials by doping of triazine containing tripodal dopant in the organic framework. These materials showed excellent CO 2 storage capacities as high as 25.5 wt% under 1 bar pressure with exceptional CO 2 /N 2 selectivity of 377. - Highlights: • Triazine containing trimodal moiety incorporated in polycarbazolic and poly triphenylamine networks. • N-rich crosslinked polymers with high BET surface area and 1.5–1.7 nm size large micropores. • CO 2 uptake capacity of 25.5 wt% upto 1 bar at 273 K. • These crosslinked porous polymers showed exceptional CO 2 /N 2 selectivity.

Synthesis of Microporous Materials and Their VSC Adsorption Properties

Energy Technology Data Exchange (ETDEWEB)

Yokogawa, Y; Morikawa, H; Sakanishi, M; Utaka, H; Nakamura, A; Kishida, I, E-mail: yokogawa@imat.eng.osaka-cu.ac.jp [Graduate School of Engineering, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka, 558-8585 (Japan)

2011-10-29

Oral malodor is caused by volatile sulfur compounds (VSC) such as hydrogen sulfide (H{sub 2}S), methyl mercaptan and dimethyl sulfide produced in mouth. VSC induces permeability of mucous membrane and oral malodor formation. Thus, the adsorbent which highly adsorbs VSC should be useful for health in mouth and may prevent teeth from decaying. The microporous material, hydrotalcite, was synthesized by a wet method, and the H{sub 2}S adsorption was studied. The samples, identified by powder X-ray diffraction method, were put into glass flask filled with H{sub 2}S gas. The initial concentration of H{sub 2}S was 30 ppm. The change in concentrations of H{sub 2}S was measured at rt, and the amount of H{sub 2}S absorbed on the hydrotalcite for 24 h was 300 micro L/g. The samples were taken out from the above glass flask and put into a pyrolysis plant attached to gas chromatography-mass spectrometry to determine the amount of H{sub 2}S desorbed from samples. Only 3% of H{sub 2}S was desorbed when heated at 500 deg. C. H{sub 2}S in water was also found to adsorb into hydrotalcite, which was confirmed by the headspace gas chromatography with flame photometric detector. The hydrotalcite material should be expected to be an adsorbent material, useful for health in mouth.

Tritium labelling of molecules constrained in microporous catalysts

International Nuclear Information System (INIS)

Long, M.A.; Garnett, J.L.; Than, Chit

1989-01-01

The use of microporous aluminophosphate catalysts for exchange between tritium gas or tritiated water and organic substrates is described. The results are compared with those of microporous zeolites. Results are interpreted in terms of the influence of the constraints imposed on molecular configuration by the catalyst pore geometry. The use of these porous structures for minimising byproduct formation in radiation induced labelling processes with tritium gas is described. (author). 10 refs.; 3 tabs

Fluvastatin as a micropore lifetime enhancer for sustained delivery across microneedle-treated skin.

Science.gov (United States)

Ghosh, Priyanka; Brogden, Nicole K; Stinchcomb, Audra L

2014-02-01

Microneedles (MNs), a physical skin permeation enhancement technique, facilitate drug delivery across the skin, thus enhancing the number of drugs that can be delivered transdermally in therapeutically relevant concentrations. The micropores created in the skin by MNs reseal because of normal healing processes of the skin, thus limiting the duration of the drug delivery window. Pore lifetime enhancement strategies can increase the effectiveness of MNs as a drug delivery mechanism by prolonging the delivery window. Fluvastatin (FLU), a HMGCoA reductase inhibitor, was used in this study to enhance the pore lifetime by inhibiting the synthesis of cholesterol, a major component of the stratum corneum lipids. The study showed that using FLU as a pretreatment it is possible to enhance the pore lifetime of MN-treated skin and thus allow for sustained drug delivery. The skin recovered within a 30-45-min time period following the removal of occlusion, and there was no significant irritation observed due to the treatment compared to the control sites. Thus, it can be concluded that localized skin treatment with FLU can be used to extend micropore lifetime and deliver drugs for up to 7 days across MN-treated skin. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Electron transfer reactions in microporous solids

Energy Technology Data Exchange (ETDEWEB)

Mallouk, T.E.

1993-01-01

Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H[sub 2] and I[sub 3][sup [minus

Microporous carbon derived from polyaniline base as anode material for lithium ion secondary battery

International Nuclear Information System (INIS)

Xiang, Xiaoxia; Liu, Enhui; Huang, Zhengzheng; Shen, Haijie; Tian, Yingying; Xiao, Chengyi; Yang, Jingjing; Mao, Zhaohui

2011-01-01

Highlights: → Nitrogen-containing microporous carbon was prepared from polyaniline base by K 2 CO 3 activation, and used as anode material for lithium ion secondary battery. → K 2 CO 3 activation promotes the formation of amorphous and microporous structure. → High nitrogen content, and large surface area with micropores lead to strong intercalation between carbon and lithium ion, and thus improve the lithium storage capacity. -- Abstract: Microporous carbon with large surface area was prepared from polyaniline base using K 2 CO 3 as an activating agent. The physicochemical properties of the carbon were characterized by scanning electron microscope, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurement. The electrochemical properties of the microporous carbon as anode material in lithium ion secondary battery were evaluated. The first discharge capacity of the microporous carbon was 1108 mAh g -1 , whose first charge capacity was 624 mAh g -1 , with a coulombic efficiency of 56.3%. After 20 cycling tests, the microporous carbon retains a reversible capacity of 603 mAh g -1 at a current density of 100 mA g -1 . These results clearly demonstrated the potential role of microporous carbon as anode for high capacity lithium ion secondary battery.

Protein adsorption onto nanozeolite: effect of micropore openings.

Science.gov (United States)

Wu, Jiamin; Li, Xiang; Yan, Yueer; Hu, Yuanyuan; Zhang, Yahong; Tang, Yi

2013-09-15

A clear and deep understanding of protein adsorption on porous surfaces is desirable for the reasonable design and applications of porous materials. In this study, the effect of surface micropores on protein adsorption was systematically investigated by comparing adsorption behavior of cytochrome c (Cyto-c) and Candida antarctica Lipase B (CALB) on porous and non-porous nanozeolites silicalite-1 and Beta. It was found that micropore openings on the surface of nanozeolites played a key role in determining adsorption affinity, conformations, and activities of proteins. Both Cyto-c and CALB showed higher affinity to porous nanozeolites than to non-porous ones, resulting in greater conformational change of proteins on porous surfaces which in turn affected their bio-catalytic performance. The activity of Cyto-c improved while that of CALB decreased on porous nanozeolites. Recognition of certain amino acid residues or size-matching secondary structures by micropore openings on the surface of nanozeolites was proposed to be the reason. Moreover, the pore opening effect of porous nanozeolites on protein behavior could be altered by changing protein coverage on them. This study gives a novel insight into the interaction between proteins and microporous materials, which will help to guide the rational fabrication and bio-applications of porous materials in the future. Copyright © 2013 Elsevier Inc. All rights reserved.

Micropore and nanopore fabrication in hollow antiresonant reflecting optical waveguides.

Science.gov (United States)

Holmes, Matthew R; Shang, Tao; Hawkins, Aaron R; Rudenko, Mikhail; Measor, Philip; Schmidt, Holger

2010-01-01

We demonstrate the fabrication of micropore and nanopore features in hollow antiresonant reflecting optical waveguides to create an electrical and optical analysis platform that can size select and detect a single nanoparticle. Micropores (4 μm diameter) are reactive-ion etched through the top SiO(2) and SiN layers of the waveguides, leaving a thin SiN membrane above the hollow core. Nanopores are formed in the SiN membranes using a focused ion-beam etch process that provides control over the pore size. Openings as small as 20 nm in diameter are created. Optical loss measurements indicate that micropores did not significantly alter the loss along the waveguide.

Microstructure investigation on micropore formation in microporous silica materials prepared via a catalytic sol-gel process by small angle X-ray scattering.

Science.gov (United States)

Shimizu, Wataru; Hokka, Junsuke; Sato, Takaaki; Usami, Hisanao; Murakami, Yasushi

2011-08-04

The so-called sol-gel technique has been shown to be a template-free, efficient way to create functional porous silica materials having uniform micropores. This appears to be closely linked with a postulation that the formation of weakly branched polymer-like aggregates in a precursor solution is a key to the uniform micropore generation. However, how such a polymer-like structure can precisely be controlled, and further, how the generated low-fractal dimension solution structure is imprinted on the solid silica materials still remain elusive. Here we present fabrication of microporous silica from tetramethyl orthosilicate (TMOS) using a recently developed catalytic sol-gel process based on a nonionic hydroxyacetone (HA) catalyst. Small angle X-ray scattering (SAXS), nitrogen adsorption porosimetry, and transmission electron microscope (TEM) allowed us to observe the whole structural evolution, ranging from polymer-like aggregates in the precursor solution to agglomeration with heat treatment and microporous morphology of silica powders after drying and hydrolysis. Using the HA catalyst with short chain monohydric alcohols (methanol or ethanol) in the precursor solution, polymer-like aggregates having microscopic correlation length (or mesh-size) micropores with diameters 2 nm) in the solid product due to apertures between the particle-like aggregates. The data demonstrate that the extremely fine porous silica architecture comes essentially from a gaussian polymer-like nature of the silica aggregates in the precursor having the microscopic mesh-size and their successful imprint on the solid product. The result offers a general but significantly efficient route to creating precisely designed fine porous silica materials under mild condition that serve as low refractive index and efficient thermal insulation materials in their practical applications.

Computer modelling of microporous materials

NARCIS (Netherlands)

Catlow, C.R.A.; Santen, van R.A.; Smit, B.

2004-01-01

Microporous materials, including both zeolites and aluminophosphates are amongst the most fascinating classes of materials, with wide ranging important applications in catalysis, gas separation and ion exchange. The breadth of the field has, moreover, been extended in the last ten years by the

The nonlinear propagation of acoustic waves in a viscoelastic medium containing cylindrical micropores

International Nuclear Information System (INIS)

Yu-Lin, Feng; Xiao-Zhou, Liu; Jie-Hui, Liu; Li, Ma

2009-01-01

Based on an equivalent medium approach, this paper presents a model describing the nonlinear propagation of acoustic waves in a viscoelastic medium containing cylindrical micropores. The influences of pores' nonlinear oscillations on sound attenuation, sound dispersion and an equivalent acoustic nonlinearity parameter are discussed. The calculated results show that the attenuation increases with an increasing volume fraction of micropores. The peak of sound velocity and attenuation occurs at the resonant frequency of the micropores while the peak of the equivalent acoustic nonlinearity parameter occurs at the half of the resonant frequency of the micropores. Furthermore, multiple scattering has been taken into account, which leads to a modification to the effective wave number in the equivalent medium approach. We find that these linear and nonlinear acoustic parameters need to be corrected when the volume fraction of micropores is larger than 0.1%

Development of an alternating magnetic-field-assisted finishing process for microelectromechanical systems micropore x-ray optics.

Science.gov (United States)

Riveros, Raul E; Yamaguchi, Hitomi; Mitsuishi, Ikuyuki; Takagi, Utako; Ezoe, Yuichiro; Kato, Fumiki; Sugiyama, Susumu; Yamasaki, Noriko; Mitsuda, Kazuhisa

2010-06-20

X-ray astronomy research is often limited by the size, weight, complexity, and cost of functioning x-ray optics. Micropore optics promises an economical alternative to traditional (e.g., glass or foil) x-ray optics; however, many manufacturing difficulties prevent micropore optics from being a viable solution. Ezoe et al. introduced microelectromechanical systems (MEMS) micropore optics having curvilinear micropores in 2008. Made by either deep reactive ion etching or x-ray lithography, electroforming, and molding (LIGA), MEMS micropore optics suffer from high micropore sidewall roughness (10-30nmrms) which, by current standards, cannot be improved. In this research, a new alternating magnetic-field-assisted finishing process was developed using a mixture of ferrofluid and microscale abrasive slurry. A machine was built, and a set of working process parameters including alternating frequency, abrasive size, and polishing time was selected. A polishing experiment on a LIGA-fabricated MEMS micropore optic was performed, and a change in micropore sidewall roughness of 9.3+/-2.5nmrms to 5.7+/-0.7nmrms was measured. An improvement in x-ray reflectance was also seen. This research shows the feasibility and confirms the effects of this new polishing process on MEMS micropore optics.

Development of an alternating magnetic-field-assisted finishing process for microelectromechanical systems micropore x-ray optics

Energy Technology Data Exchange (ETDEWEB)

Riveros, Raul E.; Yamaguchi, Hitomi; Mitsuishi, Ikuyuki; Takagi, Utako; Ezoe, Yuichiro; Kato, Fumiki; Sugiyama, Susumu; Yamasaki, Noriko; Mitsuda, Kazuhisa

2010-06-20

X-ray astronomy research is often limited by the size, weight, complexity, and cost of functioning x-ray optics. Micropore optics promises an economical alternative to traditional (e.g., glass or foil) x-ray optics; however, many manufacturing difficulties prevent micropore optics from being a viable solution. Ezoe et al. introduced microelectromechanical systems (MEMS) micropore optics having curvilinear micropores in 2008. Made by either deep reactive ion etching or x-ray lithography, electroforming, and molding (LIGA), MEMS micropore optics suffer from high micropore sidewall roughness (10-30nmrms) which, by current standards, cannot be improved. In this research, a new alternating magnetic-field-assisted finishing process was developed using a mixture of ferrofluid and microscale abrasive slurry. A machine was built, and a set of working process parameters including alternating frequency, abrasive size, and polishing time was selected. A polishing experiment on a LIGA-fabricated MEMS micropore optic was performed, and a change in micropore sidewall roughness of 9.3{+-}2.5nmrms to 5.7{+-}0.7nmrms was measured. An improvement in x-ray reflectance was also seen. This research shows the feasibility and confirms the effects of this new polishing process on MEMS micropore optics.

A study on the dissymmetrical microporous layer structure of a direct methanol fuel cell

International Nuclear Information System (INIS)

Wang Tongtao; Lin Caishun; Fang Yong; Ye Feng; Miao Ruiying; Wang Xindong

2008-01-01

The effect of carbon type, carbon loading and microporous layer structure in the microporous layer on the performance of a direct methanol fuel cell (DMFC) at low temperature was investigated using electrochemical polarization techniques, electrochemical impedance spectroscopy, scanning electron microscope and other methods. Vulcan XC-72 carbon was found to be most suitable as a microporous layer for low temperature DMFC. Maximum fuel cell performance was obtained utilizing a microporous layer with carbon loading of 1.0 mg cm -2 when air was used as an oxidant. A membrane electrode assembly with 1.0 mg cm -2 Vulcan XC-72 carbon with 20 wt.% Teflon in the cathode and no microporous layer in the anode showed a maximum power density of 36.7 mW cm -2 at 35 deg. C under atmospheric pressure. The AC impedance study proved that a cell with a dissymmetrical microporous layer structure had lower internal resistance and mass transfer resistance, thus obtaining better performance

Water-Hydrogel Binding Affinity Modulates Freeze-Drying-Induced Micropore Architecture and Skeletal Myotube Formation.

Science.gov (United States)

Rich, Max H; Lee, Min Kyung; Marshall, Nicholas; Clay, Nicholas; Chen, Jinrong; Mahmassani, Ziad; Boppart, Marni; Kong, Hyunjoon

2015-08-10

Freeze-dried hydrogels are increasingly used to create 3D interconnected micropores that facilitate biomolecular and cellular transports. However, freeze-drying is often plagued by variance in micropore architecture based on polymer choice. We hypothesized that water-polymer binding affinity plays a significant role in sizes and numbers of micropores formed through freeze-drying, influencing cell-derived tissue quality. Poly(ethylene glycol)diacrylate (PEGDA) hydrogels with alginate methacrylate (AM) were used due to AM's higher binding affinity for water than PEGDA. PEGDA-AM hydrogels with larger AM concentrations resulted in larger sizes and numbers of micropores than pure PEGDA hydrogels, attributed to the increased mass of water binding to the PEGDA-AM gel. Skeletal myoblasts loaded in microporous PEGDA-AM hydrogels were active to produce 3D muscle-like tissue, while those loaded in pure PEGDA gels were localized on the gel surface. We propose that this study will be broadly useful in designing and improving the performance of various microporous gels.

Development of an alternating magnetic-field-assisted finishing process for microelectromechanical systems micropore x-ray optics

International Nuclear Information System (INIS)

Riveros, Raul E.; Yamaguchi, Hitomi; Mitsuishi, Ikuyuki; Takagi, Utako; Ezoe, Yuichiro; Kato, Fumiki; Sugiyama, Susumu; Yamasaki, Noriko; Mitsuda, Kazuhisa

2010-01-01

X-ray astronomy research is often limited by the size, weight, complexity, and cost of functioning x-ray optics. Micropore optics promises an economical alternative to traditional (e.g., glass or foil) x-ray optics; however, many manufacturing difficulties prevent micropore optics from being a viable solution. Ezoe et al. introduced microelectromechanical systems (MEMS) micropore optics having curvilinear micropores in 2008. Made by either deep reactive ion etching or x-ray lithography, electroforming, and molding (LIGA), MEMS micropore optics suffer from high micropore sidewall roughness (10-30nmrms) which, by current standards, cannot be improved. In this research, a new alternating magnetic-field-assisted finishing process was developed using a mixture of ferrofluid and microscale abrasive slurry. A machine was built, and a set of working process parameters including alternating frequency, abrasive size, and polishing time was selected. A polishing experiment on a LIGA-fabricated MEMS micropore optic was performed, and a change in micropore sidewall roughness of 9.3±2.5nmrms to 5.7±0.7nmrms was measured. An improvement in x-ray reflectance was also seen. This research shows the feasibility and confirms the effects of this new polishing process on MEMS micropore optics.

Healing behavior of preexisting hydrogen micropores in aluminum alloys during plastic deformation

International Nuclear Information System (INIS)

Toda, H.; Minami, K.; Koyama, K.; Ichitani, K.; Kobayashi, M.; Uesugi, K.; Suzuki, Y.

2009-01-01

Synchrotron X-ray microtomography was used to observe the shrinkage and annihilation behaviors of hydrogen micropores in three dimensions during hot and cold plastic deformation of an Al-Mg alloy. Whether complete healing of micropores is achieved after plastic deformation was examined by exposing the material to a high temperature after plastic deformation. Although micropores generally show a pattern of shrinking and closing, closer inspection of a single specimen revealed a variety of geometrically variable behaviors. It is noteworthy that some of the micropores are reinitiated in positions identical to those before their annihilation, even after an 8-22% macroscopic strain has been further applied after annihilation. We attribute local variations such as these to significant local strain variation, which we measured in a series of tomographic volumes by tracking the microstructural features.

An Investigation of Porous Structure of TiNi-Based SHS-Materials Produced at Different Initial Synthesis Temperatures

Science.gov (United States)

Khodorenko, V. N.; Anikeev, S. G.; Kokorev, O. V.; Yasenchuk, Yu. F.; Gunther, V. É.

2018-02-01

An investigation of structural characteristics and behavior of TiNi-based pore-permeable materials manufactured by the methods of selfpropagating high-temperature synthesis (SHS) at the initial synthesis temperatures T = 400 and 600°C is performed. It is shown that depending on the temperature regime, the resulting structure and properties of the material can differ. It is found out that the SHS-material produced at the initial synthesis temperature T = 400°C possesses the largest number of micropores in the pore wall surface structure due to a high phase inhomogeneity of the alloy. The regime of structure optimization of the resulting materials is described and the main stages of formation of the pore wall microporous surfaces are revealed. It is demonstrated that after optimization of the surface structure of a TiNi-based fine-pore alloy by its chemical etching, the fraction of micropores measuring in size less than 50 nm increased from 59 to 68%, while the number of pores larger than 1 μm increased twofold from 11 to 22%. In addition, peculiar features of interaction between certain cell cultures with the surface of the SHS-material manufactured at different initial synthesis temperatures are revealed. It is found out that the dynamics of the cell material integration depends on the pore wall surface morphology and dimensions of macropores.

Micropore closure kinetics are delayed following microneedle insertion in elderly subjects.

Science.gov (United States)

Kelchen, Megan N; Siefers, Kyle J; Converse, Courtney C; Farley, Matthew J; Holdren, Grant O; Brogden, Nicole K

2016-03-10

Transdermal delivery is an advantageous method of drug administration, particularly for an elderly population. Microneedles (MNs) allow transdermal delivery of otherwise skin-impermeable drugs by creating transient micropores that bypass the barrier function of the skin. The response of aging skin to MNs has not been explored, and we report for the first time that micropore closure is delayed in elderly subjects in a manner that is dependent upon MN length, number, and occlusion of the micropores. Twelve control subjects (25.6±2.8years) and 16 elderly subjects (77.3±6.8years) completed the study. Subjects were treated with MNs of 500μm or 750μm length, in arrays containing 10 or 50 MNs. Impedance measurements made at baseline, post-MN insertion, and at predetermined time points demonstrated that restoration of the skin barrier is significantly slower in elderly subjects under both occluded and non-occluded conditions. This was confirmed via calculation of the total permeable area created by the micropores (which would approximate the area available for drug delivery), as well as calculation of the micropore half-life. This pilot study demonstrates that longer timeframes are required to restore the barrier function of aged skin following MN insertion, suggesting that drug delivery windows could be longer following one treatment with a MN array. Copyright © 2016 Elsevier B.V. All rights reserved.

Triazine containing N-rich microporous organic polymers for CO{sub 2} capture and unprecedented CO{sub 2}/N{sub 2} selectivity

Energy Technology Data Exchange (ETDEWEB)

Bhunia, Subhajit; Bhanja, Piyali; Das, Sabuj Kanti [Department of Material Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Sen, Tapas [Nanobiomaterials Research Group, Centre for Materials Science, School of Physical Sciences and Computing, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Bhaumik, Asim, E-mail: msab@iacs.res.in [Department of Material Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

2017-03-15

Targeted synthesis of microporous adsorbents for CO{sub 2} capture and storage is very challenging in the context of remediation from green house gases. Herein we report two novel N-rich microporous networks SB-TRZ-CRZ and SB-TRZ-TPA by extensive incorporation of triazine containing tripodal moiety in the porous polymer framework. These materials showed excellent CO{sub 2} storage capacities: SB-TRZ-CRZ displayed the CO{sub 2} uptake capacity of 25.5 wt% upto 1 bar at 273 K and SB-TRZ-TPA gave that of 16 wt% under identical conditions. The substantial dipole quadruple interaction between network (polar triazine) and CO{sub 2} boosts the selectivity for CO{sub 2}/N{sub 2}. SB-TRZ-CRZ has this CO{sub 2}/N{sub 2} selectivity ratio of 377, whereas for SB-TRZ-TPA it was 97. Compared to other porous polymers, these materials are very cost effective, scalable and very promising material for clean energy application and environmental issues. - Graphical abstract: We report two novel N-rich microporous polymeric materials by doping of triazine containing tripodal dopant in the organic framework. These materials showed excellent CO{sub 2} storage capacities as high as 25.5 wt% under 1 bar pressure with exceptional CO{sub 2}/N{sub 2} selectivity of 377. - Highlights: • Triazine containing trimodal moiety incorporated in polycarbazolic and poly triphenylamine networks. • N-rich crosslinked polymers with high BET surface area and 1.5–1.7 nm size large micropores. • CO{sub 2} uptake capacity of 25.5 wt% upto 1 bar at 273 K. • These crosslinked porous polymers showed exceptional CO{sub 2}/N{sub 2} selectivity.

Microporous metal organic framework [M2(hfipbb)2(ted)] (M=Zn, Co; H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine): Synthesis, structure analysis, pore characterization, small gas adsorption and CO2/N2 separation properties

Science.gov (United States)

Xu, William W.; Pramanik, Sanhita; Zhang, Zhijuan; Emge, Thomas J.; Li, Jing

2013-04-01

Carbon dioxide is a greenhouse gas that is a major contributor to global warming. Developing methods that can effectively capture CO2 is the key to reduce its emission to the atmosphere. Recent research shows that microporous metal organic frameworks (MOFs) are emerging as a promising family of adsorbents that may be promising for use in adsorption based capture and separation of CO2 from power plant waste gases. In this work we report the synthesis, crystal structure analysis and pore characterization of two microporous MOF structures, [M2(hfipbb)2(ted)] (M=Zn (1), Co (2); H2hfipbb=4,4-(hexafluoroisopropylidene)-bis(benzoic acid); ted=triethylenediamine). The CO2 and N2 adsorption experiments and IAST calculations are carried out on [Zn2(hfipbb)2(ted)] under conditions that mimic post-combustion flue gas mixtures emitted from power plants. The results show that the framework interacts with CO2 strongly, giving rise to relatively high isosteric heats of adsorption (up to 28 kJ/mol), and high adsorption selectivity for CO2 over N2, making it promising for capturing and separating CO2 from CO2/N2 mixtures.

Temperature-regulated guest admission and release in microporous materials

Science.gov (United States)

Li, Gang (Kevin); Shang, Jin; Gu, Qinfen; Awati, Rohan V.; Jensen, Nathan; Grant, Andrew; Zhang, Xueying; Sholl, David S.; Liu, Jefferson Z.; Webley, Paul A.; May, Eric F.

2017-06-01

While it has long been known that some highly adsorbing microporous materials suddenly become inaccessible to guest molecules below certain temperatures, previous attempts to explain this phenomenon have failed. Here we show that this anomalous sorption behaviour is a temperature-regulated guest admission process, where the pore-keeping group's thermal fluctuations are influenced by interactions with guest molecules. A physical model is presented to explain the atomic-level chemistry and structure of these thermally regulated micropores, which is crucial to systematic engineering of new functional materials such as tunable molecular sieves, gated membranes and controlled-release nanocontainers. The model was validated experimentally with H2, N2, Ar and CH4 on three classes of microporous materials: trapdoor zeolites, supramolecular host calixarenes and metal-organic frameworks. We demonstrate how temperature can be exploited to achieve appreciable hydrogen and methane storage in such materials without sustained pressure. These findings also open new avenues for gas sensing and isotope separation.

Role of binder in the synthesis of titania membrane

Indian Academy of Sciences (India)

Unknown

Abstract. The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature.

Self-assembly of an electronically conductive network through microporous scaffolds.

Science.gov (United States)

Sebastian, H Bri; Bryant, Steven L

2017-06-15

Electron transfer spanning significant distances through a microporous structure was established via the self-assembly of an electronically conductive iridium oxide nanowire matrix enveloping the pore walls. Microporous formations were simulated using two scaffold materials of varying physical and chemical properties; paraffin wax beads, and agar gel. Following infiltration into the micropores, iridium nanoparticles self-assembled at the pore wall/ethanol interface. Subsequently, cyclic voltammetry was employed to electrochemically crosslink the metal, erecting an interconnected, and electronically conductive metal oxide nanowire matrix. Electrochemical and spectral characterization techniques confirmed the formation of oxide nanowire matrices encompassing lengths of at least 1.6mm, 400× distances previously achieved using iridium nanoparticles. Nanowire matrices were engaged as biofuel cell anodes, where electrons were donated to the nanowires by a glucose oxidizing enzyme. Copyright © 2017 Elsevier Inc. All rights reserved.

Catalytic Wastewater Treatment Using Pillared Clays

Science.gov (United States)

Perathoner, Siglinda; Centi, Gabriele

After introduction on the use of solid catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), this review discussed the use of pillared clay (PILC) materials in three applications: (i) wet air catalytic oxidation (WACO), (ii) wet hydrogen peroxide catalytic oxidation (WHPCO) on Cu-PILC and Fe-PILC, and (iii) behavior of Ti-PILC and Fe-PILC in the photocatalytic or photo-Fenton conversion of pollutants. Literature data are critically analyzed to evidence the main direction to further investigate, in particularly with reference to the possible practical application of these technologies to treat industrial, municipal, or agro-food production wastewater.

Size and spatial distribution of micropores in SBA-15 using CM-SANS

International Nuclear Information System (INIS)

Pollock, Rachel A.; Walsh, Brenna R.; Fry, Jason A.; Ghampson, Tyrone; Centikol, Ozgul; Melnichenko, Yuri B.; Kaiser, Helmut; Pynn, Roger; Frederick, Brian G.

2011-01-01

Diffraction intensity analysis of small-angle neutron scattering measurements of dry SBA-15 have been combined with nonlocal density functional theory (NLDFT) analysis of nitrogen desorption isotherms to characterize the micropore, secondary mesopore, and primary mesopore structure. The radial dependence of the scattering length density, which is sensitive to isolated surface hydroxyls, can only be modeled if the NLDFT pore size distribution is distributed relatively uniformly throughout the silica framework, not localized in a 'corona' around the primary mesopores. Contrast matching-small angle neutron scattering (CM-SANS) measurements, using water, decane, tributylamine, cyclohexane, and isooctane as direct probes of the size of micropores indicate that the smallest pores in SBA-15 have diameter between 5.7 and 6.2 (angstrom). Correlation of the minimum pore size with the onset of the micropore size distribution provides direct evidence that the shape of the smallest micropores is cylinderlike, which is consistent with their being due to unraveling of the polymer template.

Asymmetric hydration structure around calcium ion restricted in micropores fabricated in activated carbons

International Nuclear Information System (INIS)

Ohkubo, Takahiro; Kusudo, Tomoko; Kuroda, Yasushige

2016-01-01

The adsorbed phase and hydration structure of an aqueous solution of Ca(NO 3 ) 2 restricted in micropores fabricated in activated carbons (ACs) having different average pore widths (0.63 and 1.1 nm) were investigated with the analysis of adsorption isotherms and x-ray absorption fine structure (XAFS) spectra on Ca K -edge. The adsorbed density of Ca 2+ per unit micropore volume in the narrower pore was higher than in the wider pore, while the adsorbed amount per unit mass of carbon with the narrower pore was half of the amount of ACs with the larger pore. On the other hand, variations in the bands assigned to double-electron ( KM I ) and 1s  →  3d excitations in XAFS spectra demonstrate the formation of a distorted hydration cluster around Ca 2+ in the micropore, although the structural parameters of hydrated Ca 2+ in the micropores were almost consistent with the bulk aqueous solution, as revealed by the analysis of extended XAFS (EXAFS) spectra. In contrast to the hydration structure of monovalent ions such as Rb + , which generally presents a dehydrated structure in smaller than 1 nm micropores in ACs, the present study clearly explains that the non-spherically-symmetric structure of hydrated Ca 2+ restricted in carbon micropores whose sizes are around 1 nm is experimentally revealed where any dehydration phenomena from the first hydration shell around Ca 2+ could not be observed. (paper)

Electrochemically deposited and etched membranes with precisely sized micropores for biological fluids microfiltration

International Nuclear Information System (INIS)

Hamzah, A A; Zainal Abidin, H E; Yeop Majlis, B; Mohd Nor, M; Ismardi, A; Sugandi, G; Tiong, T Y; Dee, C F; Yunas, J

2013-01-01

This paper presents simple and economical, yet reliable techniques to fabricate a micro-fluidic filter for MEMS lab-on-chip (LoC) applications. The microporous filter is a crucial component in a MEMS LoC system. Microsized components and contaminants in biological fluids are selectively filtered using copper and silicon membranes with precisely controlled microsized pores. Two techniques were explored in microporous membrane fabrication, namely copper electroplating and electrochemical etching (ECE) of silicon. In the first technique, a copper membrane with evenly distributed micropores was fabricated by electroplating the copper layer on the silicon nitride membrane, which was later removed to leave the freestanding microporous membrane structure. The second approach involves the thinning of bulk silicon down to a few micrometers thick using KOH and etching the resulting silicon membrane in 5% HF by ECE to create micropores. Upon testing with nanoparticles of various sizes, it was observed that electroplated copper membrane passes nanoparticles up to 200 nm wide, while porous silicon membrane passes nanoparticles up to 380 nm in size. Due to process compatibility, simplicity, and low-cost fabrication, electroplated copper and porous silicon membranes enable synchronized microfilter fabrication and integration into the MEMS LoC system. (paper)

Nanowire-integrated microporous silicon membrane for continuous fluid transport in micro cooling device

International Nuclear Information System (INIS)

So, Hongyun; Pisano, Albert P.; Cheng, Jim C.

2013-01-01

We report an efficient passive micro pump system combining the physical properties of nanowires and micropores. This nanowire-integrated microporous silicon membrane was created to feed coolant continuously onto the surface of the wick in a micro cooling device to ensure it remains hydrated and in case of dryout, allow for regeneration of the system. The membrane was fabricated by photoelectrochemical etching to form micropores followed by hydrothermal growth of nanowires. This study shows a promising approach to address thermal management challenges for next generation electronic devices with absence of external power

Flux studies on ion microporous membrane for the use of medical filtration

International Nuclear Information System (INIS)

Guo Hongying; Huang Zhengde

2002-01-01

The influences of the irradiating condition (divergent and perpendicular irradiation) and hole shapes (cylinder and cone holes) on the flux are studied for ion microporous membrane. The results show that divergent irradiation and cone hole both can improve the flux of ion microporous membrane for the use of medical filtration

Preparation of laser micropore porcine acellular dermal matrix for skin graft: an experimental study.

Science.gov (United States)

Chai, Jia-Ke; Liang, Li-Ming; Yang, Hong-Ming; Feng, Rui; Yin, Hui-Nan; Li, Feng-Yu; Sheng, Zhi-Yong

2007-09-01

In our previous study, we used composite grafts consisting of meshed porcine acellular dermal matrix (PADM) and thin split-thickness autologous epidermis to cover full thickness burn wounds in clinical practice. However, a certain degree of contraction might occur because the distribution of dermal matrix was not uniform in burn wound. In this study, we prepare a composite skin graft consisting of PADM with the aid of laser to improve the quality of healing of burn wound. PADM was prepared by the trypsin/Triton X-100 method. Micropores were produced on the PADM with a laser punch. The distance between micropores varied from 0.8, 1.0, 1.2 to 1.5mm. Full thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into six groups: micropore groups I-IV in which the wound were grafted with PADM with micropores, in four different distances, respectively and split-thickness autograft; mesh group rats received meshed PADM graft and split-thickness autograft; control group received simple split-thickness autografting. The status of wound healing was histologically observed at regular time points after surgery. The wound healing rate and contraction rate were calculated. The wound healing rate in micropore groups I and II was not statistically different from that in control group, but was significantly higher than that in mesh group 6 weeks after grafting. The wound healing rate in micropore groups III and IV was lower than that in mesh and control groups 4 and 6 weeks after grafting. The wound contraction rate in micropore groups I and II was remarkably lower than that in control group 4 and 6 weeks after surgery and it was significantly much lower than that in mesh group 6 weeks after surgery. Histological examination revealed good epithelization, regularly arranged collagenous fibers and integral structure of basement membrane. Laser micropore PADM (0.8 or 1.0mm in distance) grafting in combination with split-thickness autografting can

Track-Etched Magnetic Micropores for Immunomagnetic Isolation of Pathogens

Science.gov (United States)

Muluneh, Melaku; Shang, Wu

2014-01-01

A microfluidic chip is developed to selectively isolate magnetically tagged cells from heterogeneous suspensions, the track-etched magnetic micropore (TEMPO) filter. The TEMPO consists of an ion track-etched polycarbonate membrane coated with soft magnetic film (Ni20Fe80). In the presence of an applied field, provided by a small external magnet, the filter becomes magnetized and strong magnetic traps are created along the edges of the micropores. In contrast to conventional microfluidics, fluid flows vertically through the porous membrane allowing large flow rates while keeping the capture rate high and the chip compact. By utilizing track-etching instead of conventional semiconductor fabrication, TEMPOs can be fabricated with microscale pores over large areas A > 1 cm2 at little cost ( 500 at a flow rate of Φ = 5 mL h−1. Furthermore, the large density of micropores (ρ = 106 cm−2) allows the TEMPO to sort E. coli from unprocessed environmental and clinical samples, as the blockage of a few pores does not significantly change the behavior of the device. PMID:24535921

Role of binder in the synthesis of titania membrane

Indian Academy of Sciences (India)

The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature. The binder plays ...

Influence of surface treatments on micropore structure and hydrogen adsorption behavior of nanoporous carbons.

Science.gov (United States)

Kim, Byung-Joo; Park, Soo-Jin

2007-07-15

The scope of this work was to control the pore sizes of porous carbons by various surface treatments and to investigate the relation between pore structures and hydrogen adsorption capacity. The effects of various surface treatments (i.e., gas-phase ozone, anodic oxidation, fluorination, and oxygen plasma) on the micropore structures of porous carbons were investigated by N(2)/77 K isothermal adsorption. The hydrogen adsorption capacity was measured by H(2) isothermal adsorption at 77 K. In the result, the specific surface area and micropore volume of all of the treated samples were slightly decreased due to the micropore filling or pore collapsing behaviors. It was also found that in F(2)-treated carbons the center of the pore size distribution was shifted to left side, meaning that the average size of the micropores decreased. The F(2)- and plasma-treated samples showed higher hydrogen storage capacities than did the other samples, the F(2)-treated one being the best, indicating that the micropore size of the porous carbons played a key role in the hydrogen adsorption at 77 K.

Micropore-induced capillarity enhances bone distribution in vivo in biphasic calcium phosphate scaffolds.

Science.gov (United States)

Rustom, Laurence E; Boudou, Thomas; Lou, Siyu; Pignot-Paintrand, Isabelle; Nemke, Brett W; Lu, Yan; Markel, Mark D; Picart, Catherine; Wagoner Johnson, Amy J

2016-10-15

The increasing demand for bone repair solutions calls for the development of efficacious bone scaffolds. Biphasic calcium phosphate (BCP) scaffolds with both macropores and micropores (MP) have improved healing compared to those with macropores and no micropores (NMP), but the role of micropores is unclear. Here, we evaluate capillarity induced by micropores as a mechanism that can affect bone growth in vivo. Three groups of cylindrical scaffolds were implanted in pig mandibles for three weeks: MP were implanted either dry (MP-Dry), or after submersion in phosphate buffered saline, which fills pores with fluid and therefore suppresses micropore-induced capillarity (MP-Wet); NMP were implanted dry. The amount and distribution of bone in the scaffolds were quantified using micro-computed tomography. MP-Dry had a more homogeneous bone distribution than MP-Wet, although the average bone volume fraction, BVF‾, was not significantly different for these two groups (0.45±0.03 and 0.37±0.03, respectively). There was no significant difference in the radial bone distribution of NMP and MP-Wet, but the BVF‾, of NMP was significantly lower among the three groups (0.25±0.02). These results suggest that micropore-induced capillarity enhances bone regeneration by improving the homogeneity of bone distribution in BCP scaffolds. The explicit design and use of capillarity in bone scaffolds may lead to more effective treatments of large and complex bone defects. The increasing demand for bone repair calls for more efficacious bone scaffolds and calcium phosphate-based materials are considered suitable for this application. Macropores (>100μm) are necessary for bone ingrowth and vascularization. However, studies have shown that microporosity (micropore-induced capillarity had the potential to enhance bone growth in vivo. This work illustrates the positive effects of capillarity on bone regeneration in vivo; it demonstrates that micropore-induced capillarity significantly

Highly hydrothermally stable microporous silica membranes for hydrogen separation.

Science.gov (United States)

Wei, Qi; Wang, Fei; Nie, Zuo-Ren; Song, Chun-Lin; Wang, Yan-Li; Li, Qun-Yan

2008-08-07

Fluorocarbon-modified silica membranes were deposited on gamma-Al2O3/alpha-Al2O3 supports by the sol-gel technique for hydrogen separation. The hydrophobic property, pore structure, gas transport and separation performance, and hydrothermal stability of the modified membranes were investigated. It is observed that the water contact angle increases from 27.2+/-1.5 degrees for the pure silica membranes to 115.0+/-1.2 degrees for the modified ones with a (trifluoropropyl)triethoxysilane (TFPTES)/tetraethyl orthosilicate (TEOS) molar ratio of 0.6. The modified membranes preserve a microporous structure with a micropore volume of 0.14 cm3/g and a pore size of approximately 0.5 nm. A single gas permeation of H2 and CO2 through the modified membranes presents small positive apparent thermal activation energies, indicating a dominant microporous membrane transport. At 200 degrees C, a single H2 permeance of 3.1x10(-6) mol m(-2) s(-1) Pa(-1) and a H2/CO2 permselectivity of 15.2 were obtained after proper correction for the support resistance and the contribution from the defects. In the gas mixture measurement, the H2 permeance and the H2/CO2 separation factor almost remain constant at 200 degrees C with a water vapor pressure of 1.2x10(4) Pa for at least 220 h, indicating that the modified membranes are hydrothermally stable, benefiting from the integrity of the microporous structure due to the fluorocarbon modification.

Chelating agent-free, vapor-assisted crystallization method to synthesize hierarchical microporous/mesoporous MIL-125 (Ti).

Science.gov (United States)

McNamara, Nicholas D; Hicks, Jason C

2015-03-11

Titanium-based microporous heterogeneous catalysts are widely studied but are often limited by the accessibility of reactants to active sites. Metal-organic frameworks (MOFs), such as MIL-125 (Ti), exhibit enhanced surface areas due to their high intrinsic microporosity, but the pore diameters of most microporous MOFs are often too small to allow for the diffusion of larger reactants (>7 Å) relevant to petroleum and biomass upgrading. In this work, hierarchical microporous MIL-125 exhibiting significantly enhanced interparticle mesoporosity was synthesized using a chelating-free, vapor-assisted crystallization method. The resulting hierarchical MOF was examined as an active catalyst for the oxidation of dibenzothiophene (DBT) with tert-butyl hydroperoxide and outperformed the solely microporous analogue. This was attributed to greater access of the substrate to surface active sites, as the pores in the microporous analogues were of inadequate size to accommodate DBT. Moreover, thiophene adsorption studies suggested the mesoporous MOF contained larger amounts of unsaturated metal sites that could enhance the observed catalytic activity.

Characterization of the microporous HDPE film with a stearyl alcohol and its physical properties

International Nuclear Information System (INIS)

Park, Jong Seok; Sung, Hae Jun; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang

2009-01-01

The addition effects of the stearyl alcohol (STE) on the properties of the microporous high density polyethylene (HDPE) films were investigated. STE and dibuthyl phthalate (DBP) were premixed as a codiluent. The HDPE and the codiluent were mixed to obtain the precursor film in the twin extruder. The precursor films were uni-axially stretched up to 600% in a bath 80 .deg. C and then the stretched HDPE films were irradiated by gamma rays. The pore volume and pore size on the microporous HDPE films were increased with an increasing content of STE. The mechanical characteristics of the microporous HDPE films were increased with an irradiation dose up to 50 kGy. Also, the thermal shrinkage behavior of the microporous HDPE films was decreased with an increasing radiation dose up to 50 kGy

Subcooled flow boiling heat transfer from microporous surfaces in a small channel

International Nuclear Information System (INIS)

Yan, Sun; Li, Zhang; Hong, Xu; Xiaocheng, Zhong

2011-01-01

The continuously increasing requirement for high heat transfer rate in a compact space can be met by combining the small channel/microchannel and heat transfer enhancement methods during fluid subcooled flow boiling. In this paper, the sintered microporous coating, as an efficient means of enhancing nucleate boiling, was applied to a horizontal, rectangular small channel. Water flow boiling heat transfer characteristics from the small channel with/without the microporous coating were experimentally investigated. The small channel, even without the coating, presented flow boiling heat transfer enhancement at low vapor quality due to size effects of the channel. This enhancement was also verified by under-predictions from macro-scale correlations. In addition to the enhancement from the channel size, all six microporous coatings with various structural parameters were found to further enhance nucleate boiling significantly. Effects of the coating structural parameters, fluid mass flux and inlet subcooling were also investigated to identify the optimum condition for heat transfer enhancement. Under the optimum condition, the microporous coating could produce the heat transfer coefficients 2.7 times the smooth surface value in subcooled flow boiling and 3 times in saturated flow boiling. The combination of the microporous coating and small channel led to excellent heat transfer performance, and therefore was deemed to have promising application prospects in many areas such as air conditioning, chip cooling, refrigeration systems, and many others involving compact heat exchangers. (authors)

Preparation of Al/Fe-Pillared Clays: Effect of the Starting Mineral.

Science.gov (United States)

Muñoz, Helir-Joseph; Blanco, Carolina; Gil, Antonio; Vicente, Miguel-Ángel; Galeano, Luis-Alejandro

2017-11-28

Four natural clays were modified with mixed polyoxocations of Al/Fe for evaluating the effect of the physicochemical properties of the starting materials (chemical composition, abundance of expandable clay phases, cationic exchange capacity and textural properties) on final physicochemical and catalytic properties of Al/Fe-PILCs. The aluminosilicate denoted C2 exhibited the highest potential as starting material in the preparation of Al/Fe-PILC catalysts, mainly due to its starting cationic exchange capacity (192 meq/100 g) and the dioctahedral nature of the smectite phase. These characteristics favored the intercalation of the mixed (Al 13- x /Fe x ) 7+ Keggin-type polyoxocations, stabilizing a basal spacing of 17.4 Å and high increase of the BET surface (194 m²/g), mainly represented in microporous content. According to H₂-TPR analyses, catalytic performance of the incorporated Fe in the Catalytic Wet Peroxide Oxidation (CWPO) reaction strongly depends on the level of location in mixed Al/Fe pillars. Altogether, such physicochemical characteristics promoted high performance in CWPO catalytic degradation of methyl orange in aqueous medium at very mild reaction temperatures (25.0 ± 1.0 °C) and pressure (76 kPa), achieving TOC removal of 52% and 70% of azo-dye decolourization in only 75 min of reaction under very low concentration of clay catalyst (0.05 g/L).

Effect of a Traveling Magnetic Field on Micropore Formation in Al-Cu Alloys

Directory of Open Access Journals (Sweden)

Yanjin Xu

2018-06-01

Full Text Available The effect of traveling magnetic fields (TMFs on the grain and micro-pore formation in an Al alloy was studied by scanning electron microscope and X-ray microtomography in this work. The results show that with the increasing magnetic flux density, the three-dimensional morphology of the micro-pores transformed from dendrite to a relatively equiaxed structure. Quantified results show that both the micro-pore volume fraction and the average grain size of the primary phase decreased as the TMF density increased. The analyses show that the forced convection induced by TMF can break the dendrites, refine the grain size, and promote the liquid feeding, leading to the decrease in the volume fraction of the porosity and improved mechanical property. The TMF performed at different stages during solidification reveal that the maximum effect of TMF on reducing the micro-pore formation was found when TMF was applied in the stage of nucleation and the early stage of grain growth during solidification.

Method and electrochemical cell for synthesis and treatment of metal monolayer electrocatalysts metal, carbon, and oxide nanoparticles ion batch, or in continuous fashion

Science.gov (United States)

Adzic, Radoslav; Zhang, Junliang; Sasaki, Kotaro

2015-04-28

An apparatus and method for synthesis and treatment of electrocatalyst particles in batch or continuous fashion is provided. In one embodiment, the apparatus comprises a sonication bath and a two-compartment chamber submerged in the sonication bath. The upper and lower compartments are separated by a microporous material surface. The upper compartment comprises a cover and a working electrode (WE) connected to a Pt foil contact, with the foil contact connected to the microporous material. The upper chamber further comprises reference counter electrodes. The lower compartment comprises an electrochemical cell containing a solution of metal ions. In one embodiment, the method for synthesis of electrocatalysts comprises introducing a plurality of particles into the apparatus and applying sonication and an electrical potential to the microporous material connected to the WE. After the non-noble metal ions are deposited onto the particles, the non-noble metal ions are displaced by noble-metal ions by galvanic displacement.

Effective permeability in micropores from molecular simulations

International Nuclear Information System (INIS)

Botan, A.; Vermorel, R.; Brochard, L.; Hantal, G.; Pellenq, R.

2012-01-01

Document available in extended abstract form only. Despite many years' efforts and a large numbers of proposed models, the description of transport properties in clays is still an open question. The reason for this is that structurally clay is an extremely heterogeneous material. The pore size varies from a few to 20 angstroms for interlayer (micro) porosity, from 20 A to 500 A for interparticle (meso) porosity, and 500 A to μm and more for natural (macro) fractures. One further problem with the description of the transport properties is the presence of adsorption/desorption processes onto clay particles, which are coupled with swelling/shrinkage of the particles. Any volumetric changes in the particles affect the meso-pore aperture, and thus, the total permeability of the system. The various processes affecting the permeability occur on different spatial and temporal scales, that requires a multi-scale modeling approach. The most complete model to date is a dual porosity mode. Here the total flow is often written as a sum of the macropore flow and micropore flow. The flow through macro-pores is generally considered to be laminar and obeys Darcy's law, whereas flow through the matrix (micropore flow) may be modeled using Fick's law. The micropore flow involves both Knudsen and surface diffusion mechanisms. An accurate accounting of adsorption-desorption processes or the consideration of binary mixture greatly complicate analytical description. The goal of this study is to improve macro-scale model, the dual porosity model, for the transport properties of fluids in micropores from molecular simulations. The main idea is that we reproduce an experimental set-up used for permeability measurements, as illustrated in Figure 1. High density and low density regions are settled at each end of the membrane that allows to attain a steady flow. The densities in these regions are controlled by Grand Canonical Monte Carlo simulation; the molecular motions are described by

Physicochemical studies of silicoaluminophosphate microporous materials

International Nuclear Information System (INIS)

Durrani, S.K.; Chughtai, N.A.; Akhtar, J.; Saeed, K.; Arif, M.; Moughal, M.J.; Ahmad, M.

2000-01-01

Crystalline microporous molecular sieve materials such as alumino phosphates (AlPO/sub 4/-n) and silicoaluminophosphates (SAPO-n) are gaining tremendous importance for petroleum refining and petrochemical industries due to its fascinating catalytic and ion exchange properties. Some selected silicoaluminophosphate crystalline microporous materials topologically related to the zeolites chabazite (SAPO-34), faujasite (SAPO-37) structure and to the novel structure Pentasil-types ( SAPO-5 and SAPO-11) have been synthesized hydrothermally at an autogenous pressure and different temperatures in PTFE-lined stainless steel digestion bomb. The physico-chemical characteristics of as-synthesized and calcined products were studied using different analytical techniques such as the differential thermal analysis (DTA), thermogravimetric (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Pore size was measured by the sorption of hydrocarbon molecules (n-hexane, neopentane). The surface area, porosity, particle size and particle size distribution were resolved using BET volumetric system and laser particle size analyzer. Crystallinity and unit cell parameters of these materials were also ascertained. (author)

Bioprocess intensification of antibiotic production by Streptomyces coelicolor A3(2) in micro-porous culture

Energy Technology Data Exchange (ETDEWEB)

Ndlovu, T.M., E-mail: tm.ndlovu@nutriss.com [NUTRISS Limited, INEX, Herschel Annex, Kings Road, Newcastle upon Tyne NE1 7RU (United Kingdom); Ward, A.C. [School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Department of Microbiology, Chung-Ang University, College of Medicine, Seoul, Republic of Korea 156-756 (Korea, Republic of); Glassey, J. [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom); Eskildsen, J. [NUTRISS Limited, INEX, Herschel Annex, Kings Road, Newcastle upon Tyne NE1 7RU (United Kingdom); Akay, G. [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

2015-04-01

A novel functionalized micro-porous matrix was developed with well-controlled physicochemical proprieties such as pore size and surface chemistry. The matrix was used as a solid support in the growth of “Streptomyces coelicolor” A3(2) to enhance the production of antibiotics. The results shown support a higher production of prodigiosin and actinorhodin with overall production increase of 2–5 and 6–17, respectively, compared to conventional submerged liquid culture, offering a potential improvement in volumetric productivity. Scanning Electron Microscopy was used to evaluate pore size as well as bacterial adhesion, penetration, proliferation and migration within the micro-porous matrix. - Highlights: • Preparation of novel micro-porous matrix with different physiochemical proprieties • S. coelicolor A3(2) was cultured in those micro-porous and antibiotics was enhanced. • Matrix pore sizes and surface chemistry influenced bacterial signalling. • Bacterial signalling has a profound effect in the overproduction of Prodigiosin and actinorhodin. • Prodigiosin and actinorhodin production within micro-porous was 5–17 times higher compared with liquid growth.

Bioprocess intensification of antibiotic production by Streptomyces coelicolor A3(2) in micro-porous culture

International Nuclear Information System (INIS)

Ndlovu, T.M.; Ward, A.C.; Glassey, J.; Eskildsen, J.; Akay, G.

2015-01-01

A novel functionalized micro-porous matrix was developed with well-controlled physicochemical proprieties such as pore size and surface chemistry. The matrix was used as a solid support in the growth of “Streptomyces coelicolor” A3(2) to enhance the production of antibiotics. The results shown support a higher production of prodigiosin and actinorhodin with overall production increase of 2–5 and 6–17, respectively, compared to conventional submerged liquid culture, offering a potential improvement in volumetric productivity. Scanning Electron Microscopy was used to evaluate pore size as well as bacterial adhesion, penetration, proliferation and migration within the micro-porous matrix. - Highlights: • Preparation of novel micro-porous matrix with different physiochemical proprieties • S. coelicolor A3(2) was cultured in those micro-porous and antibiotics was enhanced. • Matrix pore sizes and surface chemistry influenced bacterial signalling. • Bacterial signalling has a profound effect in the overproduction of Prodigiosin and actinorhodin. • Prodigiosin and actinorhodin production within micro-porous was 5–17 times higher compared with liquid growth

Hierarchical mesoporous/microporous carbon with graphitized frameworks for high-performance lithium-ion batteries

Directory of Open Access Journals (Sweden)

Yingying Lv

2014-11-01

Full Text Available A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ∼2200 m2/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li+ ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.

A MICROPOROUS COATING OR STRUCTURE AND A PROCESS FOR PRODUCING IT

DEFF Research Database (Denmark)

2008-01-01

A microporous coating or structure is established as a thin metallic layer by deposition of one or more alloys on a metallic substrate, each of said alloys consisting of two or more phases, one of which can be selectively dissolved in a solution that will not significantly attack the other phase...... or phases. Such microporous coatings or structures are useful in the production of various product types, such as fuel cells, catalysts, microfilters, heat exchangers, micro-components and heat transfer devices....

Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation.

Science.gov (United States)

Zeng, Zhirui; Tice, Michael M

2018-01-01

Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms. Key Words: Microbial iron reduction-Micropore-Electron transfer strategies-Microbial carbonate. Astrobiology 18, 28-36.

The synergistic effects of carbon coating and micropore structure on the microwave absorption properties of Co/CoO nanoparticles.

Science.gov (United States)

Xie, Xiubo; Pang, Yu; Kikuchi, Hiroaki; Liu, Tong

2016-11-09

25 nm carbon-coated microporous Co/CoO nanoparticles (NPs) were synthesized by integrating chemical de-alloying and chemical vapor deposition (CVD) methods. The NPs possess micropores of 0.8-1.5 nm and display a homogeneous carbon shell of about 4 nm in thickness with a low graphitization degree. The saturation magnetization (M S ) and coercivity (H C ) of the NPs were 70.3 emu g -1 and 398.4 Oe, respectively. The microporous Co/CoO/C NPs exhibited enhanced microwave absorption performance with a minimum reflection coefficient (RC) of -78.4 dB and a wide absorption bandwidth of 8.1 GHz (RC ≤ -10 dB), larger than those of the nonporous counterparts of -68.3 dB and 5.8 GHz. The minimum RC values of the microporous Co/CoO/C NPs at different thicknesses were much smaller than the nonporous counterparts. The high microwave absorption mechanism of the microporous Co/CoO/C nanocomposite can be interpreted in terms of the interfacial polarization relaxation of the core/shell and micropore structures, the effective permittivity modification of the air in the micropores and the polarization relaxation of the defects in the low-graphitization carbon shell and the porous Co NPs. Our study demonstrates that the microporous Co/CoO/C nanocomposite is an efficient microwave absorber with high absorption intensity and wide absorption bandwidth.

Intrinsically Microporous Polymer Membranes for High Performance Gas Separation

KAUST Repository

Swaidan, Raja

2014-01-01

This dissertation addresses the rational design of intrinsically microporous solutionprocessable polyimides and ladder polymers for highly permeable and highly selective gas transport in cornerstone applications of membrane-based gas separation

An analysis of burn-off impact on the structure microporous of activated carbons formation

Science.gov (United States)

Kwiatkowski, Mirosław; Kopac, Türkan

2017-12-01

The paper presents the results on the application of the LBET numerical method as a tool for analysis of the microporous structure of activated carbons obtained from a bituminous coal. The LBET method was employed particularly to evaluate the impact of the burn-off on the obtained microporous structure parameters of activated carbons.

Preparation of micro-porous gel polymer for lithium ion polymer battery

International Nuclear Information System (INIS)

Kim, Je Young; Kim, Seok Koo; Lee, Seung-Jin; Lee, Sang Young; Lee, Hyang Mok; Ahn, Soonho

2004-01-01

We have developed a micro-porous gelling polymer layer which is formed on both the sides of support polyolefin separator with wet or dry processing technique. Morphologies of gel-coated layer are dependent on the compositions and process conditions, such as solvent/non-solvent combination and stretching ratios. The micro-porous gelling layer is used for the assembly of the lithium ion polymer battery of LG Chemical Ltd. The structure of battery is given elsewhere and the battery has excellent discharge performance with 94% of 2C discharge performance at room temperature

Effects of CO2 activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

International Nuclear Information System (INIS)

Lee, Seul-Yi; Park, Soo-Jin

2013-01-01

In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO 2 gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO 2 activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO 2 activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO 2 activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m 2 /g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO 2 activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs

The iron member of the CPO-27 coordination polymer series: Synthesis, characterization, and intriguing redox properties

DEFF Research Database (Denmark)

Märcz, Matthias; Johnsen, Rune; Dietzel, Pascal D.C.

2012-01-01

The microporous coordination polymer CPO-27-Fe was synthesized from iron salts and 2,5-dihydroxyterephthalic acid by microwave assisted solvothermal synthesis. The crystal structures of the as-synthesized compounds were determined by Rietveld refinement from powder X-ray diffraction data using...

Random lasing of microporous surface of Cr2+:ZnSe crystal induced by femtosecond laser

International Nuclear Information System (INIS)

Yang, Xianheng; Feng, Guoying; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan

2015-01-01

We demonstrate a random lasing emission based on microporous surface of Cr 2+ :ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10 −4 Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ∼13 μm and smaller ones with ∼1.2 μm on the surface of Cr 2+ :ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr 2+ :ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr 2+ :ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength

Development of in vivo impedance spectroscopy techniques for measurement of micropore formation following microneedle insertion.

Science.gov (United States)

Brogden, Nicole K; Ghosh, Priyanka; Hardi, Lucia; Crofford, Leslie J; Stinchcomb, Audra L

2013-06-01

Microneedles (MNs) provide a minimally invasive means to enhance skin permeability by creating micron-scale channels (micropores) that provide a drug delivery pathway. Adequate formation of the micropores is critical to the success of this unique drug delivery technique. The objective of the current work was to develop sensitive and reproducible impedance spectroscopy techniques to monitor micropore formation in animal models and human subjects. Hairless guinea pigs, a Yucatan miniature pig, and human volunteers were treated with 100 MN insertions per site following an overnight prehydration period. Repeated measurements were made pre- and post-MN treatment using dry and gel Ag/AgCl electrodes applied with light verses direct pressure to hold the electrode to the skin surface. Impedance measurements dropped significantly post-MN application at all sites (p micropore formation. In the Yucatan pig and human subjects, gel electrodes with direct pressure yielded the lowest variability (demonstrated by lower %relative standard deviation), whereas dry electrodes with direct pressure were superior in the guinea pigs. These studies confirm that impedance measurements are suitable for use in both clinical and animal research environments to monitor the formation of new micropores that will allow for drug delivery through the impermeable skin layers. Copyright © 2013 Wiley Periodicals, Inc.

Microporous calcium phosphate ceramics driving osteogenesis through surface architecture.

Science.gov (United States)

Zhang, Jingwei; Barbieri, Davide; ten Hoopen, Hetty; de Bruijn, Joost D; van Blitterswijk, Clemens A; Yuan, Huipin

2015-03-01

The presence of micropores in calcium phosphate (CaP) ceramics has shown its important role in initiating inductive bone formation in ectopic sites. To investigate how microporous CaP ceramics trigger osteoinduction, we optimized two biphasic CaP ceramics (i.e., BCP-R and BCP-S) to have the same chemical composition, equivalent surface area per volume, comparable protein adsorption, similar ion (i.e., calcium and phosphate) exchange and the same surface mineralization potential, but different surface architecture. In particular, BCP-R had a surface roughness (Ra) of 325.4 ± 58.9 nm while for BCP-S it was 231.6 ± 35.7 nm. Ceramic blocks with crossing or noncrossing channels of 250, 500, 1000, and 2000 µm were implanted in paraspinal muscle of dogs for 12 weeks. The percentage of bone volume in the channels was not affected by the type of pores (i.e., crossing vs. closed) or their size, but it was greatly influenced by the ceramic type (i.e., BCP-R vs. BCP-S). Significantly, more bone was formed in the channels of BCP-R than in those of BCP-S. Since the two CaP ceramics differed only in their surface architecture, the results hereby demonstrate that microporous CaP ceramics may induce ectopic osteogenesis through surface architecture. © 2014 Wiley Periodicals, Inc.

Interaction of actinides with natural microporous materials: a review

International Nuclear Information System (INIS)

Misaelides, P.; Godelitsas, A.

1998-01-01

Natural microporous materials include several types of minerals such as zeolites, clay minerals, micas, iron- and manganese-oxides/hydroxides/oxyhydroxides present in various geological environments and soil formations. The transport of the actinide elements in the environment is mainly performed through aquatic pathways (streams, rivers, underground waters) and their mobility is strongly related to the interaction of their dissolved species with geological materials and especially with the highly sorptive microporous minerals. The existing studies mainly concern the sorption of Th, U, Np, Pu and Am from aqueous media by clay minerals and zeolites as well as the determination of the corresponding chemical processes taking place at the mineral-water interface. The investigation techniques also include advanced spectroscopic methods such as Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS), Rutherford Backscattered Spectroscopy (RBS), X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy. These techniques significantly contribute to the characterization of the reacted mineral surfaces and to the explanation of the structural and compositional characteristics of the sorbed actinide species. Theoretical models regarding the aqueous chemistry and speciation of the actinides have also been developed aiming the elucidation of the complex actinide sorption mechanisms. Finally, this contribution also includes some recently obtained data concerning the interaction of actinides with todorokite (a naturally occurring microporous manganese-oxide of technological importance) and granitic micas (biotite) correlated with the nuclear waste disposal in geological formations

Silicon Micropore-Based Parallel Plate Membrane Oxygenator.

Science.gov (United States)

Dharia, Ajay; Abada, Emily; Feinberg, Benjamin; Yeager, Torin; Moses, Willieford; Park, Jaehyun; Blaha, Charles; Wright, Nathan; Padilla, Benjamin; Roy, Shuvo

2018-02-01

Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O 2 min -1 m -2 cm Hg -1 with pure water and 1.71 ± 1.03 mL O 2 min -1 m -2 cm Hg -1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Microporous membranes from polyolefin-polyamide blend materials

Czech Academy of Sciences Publication Activity Database

Meier-Haack, J.; Valko, M.; Lunkwitz, K.; Bleha, Miroslav

2004-01-01

Roč. 163, 1-3 (2004), s. 215-221 ISSN 0011-9164. [Membrane Science and Technology Conference PERMEA 2003. Tatranské Matliare, 07.09.2003-11.09.2003] Institutional research plan: CEZ:AV0Z4050913 Keywords : microporous membranes * polypropylene polyamide blends * reactive extrusion Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.057, year: 2004

Property comparisons of commercially available silica-based microporous insulations I. Machinability and thermal dimensional stability

International Nuclear Information System (INIS)

Kramer, Daniel P.; McNeil, Dennis C.; Ruhkamp, Joseph D.; Wells, Donna J.; Stringer, Robert L.; Howell, Edwin I.

2002-01-01

Maximizing the thermal to electrical conversion efficiency of a nuclear space power system requires that all of the available thermal energy be utilized in the most efficient manner. Microporous insulations are attractive for application in space power systems due to their very low thermal conductivity. Over the last few years, several new silica-based microporous insulating materials have become commercially available. Property comparisons of the various insulations obtained from company literature and experiments on microporous sample specimens are discussed. The results demonstrate that their machinability and thermal dimensional stability as a function of time at temperature and atmosphere are dependent on the particular material

Determination of Energy Characteristic and Microporous Volume by Immersion Calorimetry in Carbon Monoliths

Directory of Open Access Journals (Sweden)

Juan Carlos Moreno-Piraján

2012-01-01

Full Text Available Activated carbon monoliths disc and honeycomb type were prepared by chemical activation of coconut shell with zinc chloride at different concentrations, without using a binder. The structures were characterized by N2 adsorption at 77 K and immersion calorimetry into benzene. The experimental results showed that the activation with zinc chloride produces a wide microporous development, with micropore volume between 0,38 and 0,79 cm3g-1, apparent BET surface area between 725 and 1523 m2g-1 and immersion enthalpy between 73,5 and 164,2 Jg-1. We compared the experimental enthalpy with calculated enthalpy by equation Stoeckli-Kraehenbuehl finding a data dispersion from which can infer that the structures are not purely microporous; this fact is ratified with similar behavior that the evidence t the product EoWo.

Tadalafil inclusion in microporous silica as effective dissolution enhancer: optimization of loading procedure and molecular state characterization.

Science.gov (United States)

Mehanna, Mohammed M; Motawaa, Adel M; Samaha, Magda W

2011-05-01

Tadalafil is an efficient drug used to treat erectile dysfunction characterized by poor water solubility, which has a negative influence on its bioavailability. Utilization of microporous silica represents an effective and facile technology to increase the dissolution rate of poorly soluble drugs. Our strategy involved directly introducing tadalafil as guest molecule into microporous silica as host material by incipient wetness impregnation method. To optimize tadalafil inclusion, response surface methodology (RSM) using 3(3) factorial design was utilized. Furthermore, to investigate the molecular state of tadalafil, Fourier-transform infrared spectroscopy, differential scanning calorimetery, thermal gravimetrical analysis, nitrogen adsorption, and powder X-ray diffraction (PXRD) were carried out. The results obtained pointed out that the quantity of microporous silica was the predominant factor that increased the loading efficiency. For the optimized formula, the loading efficiency was 42.50 wt %. Adsorption-desorption experiments indicated that tadalafil has been introduced into the micropores. Powder XRD and differential scanning calorimetry analyses revealed that tadalafil is arranged in amorphous form. In addition, the dissolution rate of tadalafil from the microporous silica was faster than that of free drug. Amorphous tadalafil occluded in microporous silica did not crystallize over 3 months. These findings contributed in opening a new strategy concerning the utilization of porous silica for the dissolution rate enhancement. Copyright © 2010 Wiley-Liss, Inc.

Hydrothermal Synthesis and Characterization of a Metal-Organic Framework by Thermogravimetric Analysis, Powder X-Ray Diffraction, and Infrared Spectroscopy: An Integrative Inorganic Chemistry Experiment

Science.gov (United States)

Crane, Johanna L.; Anderson, Kelly E.; Conway, Samantha G.

2015-01-01

This advanced undergraduate laboratory experiment involves the synthesis and characterization of a metal-organic framework with microporous channels that are held intact via hydrogen bonding of the coordinated water molecules. The hydrothermal synthesis of Co[subscript 3](BTC)[subscript 2]·12H[subscript 2]O (BTC = 1,3,5-benzene tricarboxylic acid)…

Application of new nuclear track microporous membrane in transdermal therapeutic system (TTS)

International Nuclear Information System (INIS)

Risheng Wu; Jian Zhou; Wei Ke

1993-01-01

Newly-developed Nuclear Track Microporous Membrane, which is formed by alpha particle irradiation with greatly reduced cost, is first used as the drug release rate controlling membrane for TTS patch. It shows good zero order release kinetics and its released quantity of drugs can be regulated conveniently by changing its porosity instead of changing the area of other control membrane used abroad. Its high benefit-cost ratio and improved TTS performances manifest the superiority and great potential of the newly developed Nuclear Track Microporous membrane. (Author)

Fabrication of interconnected microporous biomaterials with high hydroxyapatite nanoparticle loading

International Nuclear Information System (INIS)

Zhang Wei; Yao Donggang; Zhang Qingwei; Lelkes, Peter I; Zhou, Jack G

2010-01-01

Hydroxyapatite (HA) is known to promote osteogenicity and enhance the mechanical properties of biopolymers. However, incorporating a large amount of HA into a porous biopolymer still remains a challenge. In the present work, a new method was developed to produce interconnected microporous poly(glycolic-co-lactic acid) (PLGA) with high HA nanoparticle loading. First, a ternary blend comprising PLGA/PS (polystyrene)/HA (40/40/20 wt%) was prepared by melt blending under conditions for formation of a co-continuous phase structure. Next, a dynamic annealing stage under small-strain oscillation was applied to the blend to facilitate nanoparticle redistribution. Finally, the PS phase was sacrificially extracted, leaving a porous matrix. The results from different characterizations suggested that the applied small-strain oscillation substantially accelerated the migration of HA nanoparticles during annealing from the PS phase to the PLGA phase; nearly all HA particles were uniformly presented in the PLGA phase after a short period of annealing. After dissolution of the PS phase, a PLGA material with interconnected microporous structure was successfully produced, with a high HA loading above 30 wt%. The mechanisms beneath the experimental observations, particularly on the enhanced particle migration process, were discussed, and strategies for producing highly particle loaded biopolymers with interconnected microporous structures were proposed.

An activated microporous carbon prepared from phenol-melamine-formaldehyde resin for lithium ion battery anode

International Nuclear Information System (INIS)

Zhu, Yinhai; Xiang, Xiaoxia; Liu, Enhui; Wu, Yuhu; Xie, Hui; Wu, Zhilian; Tian, Yingying

2012-01-01

Highlights: ► Microporous carbon was prepared by chemical activation of phenol-melamine-formaldehyde resin. ► Activation leads to high surface area, well-developed micropores. ► Micropores lead to strong intercalation between carbon and lithium ion. ► Large surface area promotes to improve the lithium storage capacity. -- Abstract: Microporous carbon anode materials were prepared from phenol-melamine-formaldehyde resin by ZnCl 2 and KOH activation. The physicochemical properties of the obtained carbon materials were characterized by scanning electron microscope, X-ray diffraction, Brunauer–Emmett–Teller, and elemental analysis. The electrochemical properties of the microporous carbon as anode materials in lithium ion secondary batteries were evaluated. At a current density of 100 mA g −1 , the carbon without activation shows a first discharge capacity of 515 mAh g −1 . After activation, the capacity improved obviously. The first discharge capacity of the carbon prepared by ZnCl 2 and KOH activation was 1010 and 2085 mAh g −1 , respectively. The reversible capacity of the carbon prepared by KOH activation was still as high as 717 mAh g −1 after 20 cycles, which was much better than that activated by ZnCl 2 . These results demonstrated that it may be a promising candidate as an anode material for lithium ion secondary batteries.

Effects of CO{sub 2} activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

Energy Technology Data Exchange (ETDEWEB)

Lee, Seul-Yi; Park, Soo-Jin, E-mail: sjpark@inha.ac.kr

2013-11-15

In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO{sub 2} gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO{sub 2} activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO{sub 2} activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO{sub 2} activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m{sup 2}/g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO{sub 2} activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs.

Meso- and micropore characteristics of coal lithotypes: Implications for CO2 adsorption

Science.gov (United States)

Mastalerz, Maria; Drobniak, A.; Rupp, J.

2008-01-01

Lithotypes (vitrain, clarain, and fusain) of high volatile bituminous Pennsylvanian coals (Ro of 0.56-0.62%) from Indiana (the Illinois Basin) have been studied with regard to meso- and micropore characteristics using low-pressure nitrogen and carbon dioxide adsorption techniques, respectively. High-pressure CO2 adsorption isotherms were obtained from lithotypes of the Lower Block Coal Member (the Brazil Formation) and the Springfield Coal Member (the Petersburg Formation), and after evacuation of CO2, the lithotypes were re-analyzed for meso- and micropore characteristics to investigate changes related to high-pressure CO2 adsorption. Coal lithotypes have differing Brunauer-Emmett-Teller (BET) surface areas and mesopore volumes, with significantly lower values in fusains than in vitrains or clarains. Fusains have very limited pore volume in the pore size width of 4-10 nm, and the volume, increases with an increase in pore size, in contrast to vitrain, for which a 4-10 nm range is the dominant pore'Wlidth. For clarain, both pores of 4-10 nm and pores larger than 20 nm contribute substantially to the mesoporosity. Micropore surface areas are the smallest for fusain (from 72.8 to 98.2 m2/g), largest for vitrain (from 125.0 to,158.4 m2 /g), and intermediate for clarain (from 110.5 to 124.4 m2/g). Similar relationships are noted for micropore volumes, and the lower values of these parameters in fusains are related to smaller volumes of all incremental micropore sizes. In the Springfield and the Lower Block Coal Members, among lithotypes studied, fusain has the lowest adsorption capacity. For the Lower Block, vitrain has significantly higher adsorption capacity than fusain and clarain, whereas for the Springfield, vitrain and clarain have comparable but still significantly higher adsorption capacities than fusain. The Lower Block vitrain and fusain have much higher adsorption capacities than those in the Springfield, whereas the clarains of the two coals are comparable

Triptycene dimethyl-bridgehead dianhydride-based intrinsically microporous hydroxyl-functionalized polyimide for natural gas upgrading

KAUST Repository

Alghunaimi, Fahd

2016-07-28

The synthesis and gas permeation properties of a high-performance hydroxyl-functionalized PIM-polyimide (TDA1-APAF) prepared from a novel 9,10-dimethyl-2,3,6,7-triptycene tetracarboxylic dianhydride (TDA1) and a commercially available 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (APAF) diamine monomer are reported. The microporous polymer had a BET surface area based on nitrogen adsorption of 260 m2 g−1. A freshly prepared sample exhibited excellent gas permeation properties: (i) CO2 permeability of 40 Barrer coupled with a CO2/CH4 selectivity of 55 and (ii) H2 permeability of 94 Barrer with a H2/CH4 selectivity of 129. Physical aging over 250 days resulted in significantly enhanced CO2/CH4 and H2/CH4 selectivities of 75 and 183, respectively with only ~ 25% loss in CO2 and H2 permeability. Aged TDA1-APAF exhibited 5-fold higher pure-gas CO2 permeability (30 Barrer) and two-fold higher CO2/CH4 permselectivity over conventional dense cellulose triacetate membranes at 2 bar. In addition, TDA1-APAF polyimide had a N2/CH4 selectivity of 2.3, thereby making it potentially possible to bring natural gas with low, but unacceptable nitrogen content to pipeline specification. Gas mixture permeation experiments with a 1:1 CO2/CH4 feed mixture demonstrated higher mixed- than pure-gas selectivity and plasticization resistance up to 30 bar. These results suggest that intrinsically microporous hydroxyl-functionalized triptycene-based polyimides are promising candidate membrane materials for removal of CO2 from natural gas and hydrogen purification in petrochemical refinery applications.

Properties of electrolytes in the micropores of activated carbon

International Nuclear Information System (INIS)

Kastening, Bertel; Heins, Matthias

2005-01-01

The dependence of the composition of aqueous electrolytes in the pore system of activated carbon on the potential has been determined by monitoring the amount of ions exchanged with the external electrolyte upon immersion and upon changing the electrode potential. From the investigation with KF solutions, a quantity δ/√ε = 4 x 10 -10 m is evaluated where δ is half the width of the micropores, and ε the (relative) permittivity. This is in accordance with δ ∼ 1 nm and ε ∼ 7 applying to essentially immobilized water and fits into the results with the other electrolytes. Anions are adsorbed in the cases of sodium perchlorate and potassium hydroxide, while protons are adsorbed in the case of acids (HCl, H 2 SO 4 ). The adsorption of ClO 4 - seems to result from electrostatic interaction with the solid, while H + and OH - are strongly chemisorbed, probably at surface groups like >CO. Ionic mobilities of ions in the micropores have been determined from conductance measurements concerning the pore electrolyte of a single spherical particle of activated carbon. Mobilities are more than one order of magnitude lower than those in bulk electrolyte, probably due to an increased viscosity of the liquid in the narrow pores and/or to the coulombic interaction with charged domains of the solid. The rate of charging of the capacitor (solid/micropore electrolyte) is assisted by macropores distributing ions throughout the carbon material

Random lasing of microporous surface of Cr{sup 2+}:ZnSe crystal induced by femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Yang, Xianheng; Feng, Guoying, E-mail: guoing-feng@scu.edu.cn, E-mail: zhoush@scu.edu.cn; Yao, Ke; Yi, Jiayu; Zhang, Hong [College of Electronics and Information Engineering, Sichuan University, Chengdu 610065 (China); Zhou, Shouhuan, E-mail: guoing-feng@scu.edu.cn, E-mail: zhoush@scu.edu.cn [College of Electronics and Information Engineering, Sichuan University, Chengdu 610065 (China); North China Research Institute of Electro-Optics, Beijing 100015 (China)

2015-06-15

We demonstrate a random lasing emission based on microporous surface of Cr{sup 2+}:ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10{sup −4} Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ∼13 μm and smaller ones with ∼1.2 μm on the surface of Cr{sup 2+}:ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr{sup 2+}:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr{sup 2+}:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength.

Microporous ceramic coated separators with superior wettability for enhancing the electrochemical performance of sodium-ion batteries

Science.gov (United States)

Suharto, Yustian; Lee, Yongho; Yu, Ji-Sang; Choi, Wonchang; Kim, Ki Jae

2018-02-01

Finding an alternative to glass fiber (GF) separators is a crucial factor for the fast commercialization of sodium-ion batteries (SIBs), because GF separators are too thick for use in SIBs, thereby decreasing the volumetric and gravimetric energy density. Here we propose a microporous composite separator prepared by introducing a polymeric coating layer of polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP co-polymer) with ZrO2 nanoparticles to a polyethylene (PE) separator. The coated separator efficiently enhances the cell performance of SIBs. The ZrO2 nanoparticles, finely dispersed on the polymeric coating layer, induce the formation of many micropores on the polymeric coating layer, suggesting that micropore formation on the coating layer renders the composite separator more open in structure. An ethylene carbonate/propylene carbonate liquid electrolyte for SIBs is not absorbed by PE separators even after 1 h of electrolyte droplet testing, while the proposed separator with many micropores is completely wetted by the electrolyte. Sodium ion migration across the composite separator is therefore effectively enhanced by the formation of ion transfer pathways, which improve ionic conductivity. As a result, the microporous composite separator affords stable cycle performances and excellent specific capacity retention (95.8%) after 50 cycles, comparable to those offered by a SIB with a GF separator.

Functional microporous materials of metal carboxylate: Gas-occlusion properties and catalytic activities

International Nuclear Information System (INIS)

Mori, Wasuke; Sato, Tomohiko; Ohmura, Tesushi; Nozaki Kato, Chika; Takei, Tohru

2005-01-01

Copper(II) terephthalate is the first transition metal complex found capable of adsorbing gases. This complex has opened the new field of adsorbent complex chemistry. It is recognized as the lead complex in the construction of microporous complexes. This specific system has been expanded to a systematic series of derivatives of other isomorphous transition metals, molybdenum(II), ruthenium(II, III), and rhodium(II). These complexes with open frameworks are widely recognized as very useful materials for applications to catalysis, separation at molecular level, and gas storage. - Graphical abstract: Novel microporous intramolecular reaction systems

Molecular Simulation of Adsorption in Microporous Materials

OpenAIRE

Yiannourakou M.; Ungerer P.; Leblanc B.; Rozanska X.; Saxe P.; Vidal-Gilbert S.; Gouth F.; Montel F.

2013-01-01

The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications of Monte-Carlo simulation techniques, applied to the adsorption of fluids in microporous solids such as zeolites and model carbons (pores < 2 nm). Adsorption was computed in the Grand Canonical ensemble ...

Interface physics in microporous media : LDRD final report.

Energy Technology Data Exchange (ETDEWEB)

Yaklin, Melissa A.; Knutson, Chad E.; Noble, David R.; Aragon, Alicia R.; Chen, Ken Shuang; Giordano, Nicholas J. (Purdue University, West Lafayette, IN); Brooks, Carlton, F.; Pyrak-Nolte, Laura J. (Purdue University, West Lafayette, IN); Liu, Yihong (Purdue University, West Lafayette, IN)

2008-09-01

This document contains a summary of the work performed under the LDRD project entitled 'Interface Physics in Microporous Media'. The presence of fluid-fluid interfaces, which can carry non-zero stresses, distinguishes multiphase flows from more readily understood single-phase flows. In this work the physics active at these interfaces has been examined via a combined experimental and computational approach. One of the major difficulties of examining true microporous systems of the type found in filters, membranes, geologic media, etc. is the geometric uncertainty. To help facilitate the examination of transport at the pore-scale without this complication, a significant effort has been made in the area of fabrication of both two-dimensional and three-dimensional micromodels. Using these micromodels, multiphase flow experiments have been performed for liquid-liquid and liquid-gas systems. Laser scanning confocal microscopy has been utilized to provide high resolution, three-dimensional reconstructions as well as time resolved, two-dimensional reconstructions. Computational work has focused on extending lattice Boltzmann (LB) and finite element methods for probing the interface physics at the pore scale. A new LB technique has been developed that provides over 100x speed up for steady flows in complex geometries. A new LB model has been developed that allows for arbitrary density ratios, which has been a significant obstacle in applying LB to air-water flows. A new reduced order model has been developed and implemented in finite element code for examining non-equilibrium wetting in microchannel systems. These advances will enhance Sandia's ability to quantitatively probe the rich interfacial physics present in microporous systems.

Preparation and characterization of PMMA graded microporous foams via one-step supercritical carbon dioxide foaming

International Nuclear Information System (INIS)

Yuan Huan; Li Junguo; Xiong Yuanlu; Luo Guoqiang; Shen Qiang; Zhang Lianmeng

2013-01-01

Supercritical carbon dioxide (ScCO 2 ) foaming which is inexpensive and environmental friendly has been widely used to prepare polymer-based microporous materials. In this paper, PMMA graded microporous materials were foamed by PMMA matrix after an unstable saturation process which was done under supercritical condition of 28MPa and 50 °C. The scanning electron microscopy (SEM) was utilized to observe the morphology of the graded foam. A gas adsorption model was proposed to predict the graded gas concentration in the different region of the polymer matrix. The SEM results showed that the solid and foam region of the graded foam can be connected without laminated layers. With the increasing thickness position of the graded microporous foam, the cell size increased from 3.4 to 27.5 μm, while the cell density decreased from 1.04 × 10 9 to 1.96 × 10 7 cells/cm 3 . It also found that the gradient microporous structure of the foam came from graded gas concentration which was obtained in the initial saturation process.

Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies.

Science.gov (United States)

Li, Changyi; Meckler, Stephen M; Smith, Zachary P; Bachman, Jonathan E; Maserati, Lorenzo; Long, Jeffrey R; Helms, Brett A

2018-02-01

Many forward-looking clean-energy technologies hinge on the development of scalable and efficient membrane-based separations. Ongoing investment in the basic research of microporous materials is beginning to pay dividends in membrane technology maturation. Specifically, improvements in membrane selectivity, permeability, and durability are being leveraged for more efficient carbon capture, desalination, and energy storage, and the market adoption of membranes in those areas appears to be on the horizon. Herein, an overview of the microporous materials chemistry driving advanced membrane development, the clean-energy separations employing them, and the theoretical underpinnings tying membrane performance to membrane structure across multiple length scales is provided. The interplay of pore architecture and chemistry for a given set of analytes emerges as a critical design consideration dictating mass transport outcomes. Opportunities and outstanding challenges in the field are also discussed, including high-flux 2D molecular-sieving membranes, phase-change adsorbents as performance-enhancing components in composite membranes, and the need for quantitative metrologies for understanding mass transport in heterophasic materials and in micropores with unusual chemical interactions with analytes of interest. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pt thermal atomic layer deposition for silicon x-ray micropore optics.

Science.gov (United States)

Takeuchi, Kazuma; Ezoe, Yuichiro; Ishikawa, Kumi; Numazawa, Masaki; Terada, Masaru; Ishi, Daiki; Fujitani, Maiko; Sowa, Mark J; Ohashi, Takaya; Mitsuda, Kazuhisa

2018-04-20

We fabricated a silicon micropore optic using deep reactive ion etching and coated by Pt with atomic layer deposition (ALD). We confirmed that a metal/metal oxide bilayer of Al 2 O 3 ∼10  nm and Pt ∼20  nm was successfully deposited on the micropores whose width and depth are 20 μm and 300 μm, respectively. An increase of surface roughness of sidewalls of the micropores was observed with a transmission electron microscope and an atomic force microscope. X-ray reflectivity with an Al Kα line at 1.49 keV before and after the deposition was measured and compared to ray-tracing simulations. The surface roughness of the sidewalls was estimated to increase from 1.6±0.2  nm rms to 2.2±0.2  nm rms. This result is consistent with the microscope measurements. Post annealing of the Pt-coated optic at 1000°C for 2 h showed a sign of reduced surface roughness and better angular resolution. To reduce the surface roughness, possible methods such as the annealing after deposition and a plasma-enhanced ALD are discussed.

Detecting a single molecule using a micropore-nanopore hybrid chip.

Science.gov (United States)

Liu, Lei; Zhu, Lizhong; Ni, Zhonghua; Chen, Yunfei

2013-11-21

Nanopore-based DNA sequencing and biomolecule sensing have attracted more and more attention. In this work, novel sensing devices were built on the basis of the chips containing nanopore arrays in polycarbonate (PC) membranes and micropores in Si3N4 films. Using the integrated chips, the transmembrane ionic current induced by biomolecule's translocation was recorded and analyzed, which suggested that the detected current did not change linearly as commonly expected with increasing biomolecule concentration. On the other hand, detailed translocation information (such as translocation gesture) was also extracted from the discrete current blockages in basic current curves. These results indicated that the nanofluidic device based on the chips integrated by micropores and nanopores possessed comparative potentials in biomolecule sensing.

Synthesis of microporous material faujasite-type from kaolin waste

International Nuclear Information System (INIS)

Hildebrando, E.A.; Valenzuela-Diaz, F.R.; Angelica, R.S.; Neves, R.F.

2010-01-01

Zeolite with structure faujasite was synthesized using kaolin waste from kaolin processing industries for paper coating as predominant source of silicon and aluminum; the starting material was characterized by XRF, XRD, DTA/TG, SEM, and products obtained by XRD and SEM. Synthesis in hydrothermal conditions occurred on autoclave and time-temperature effects, as well as the relationship Si/Al were considered. The results show that the methodology developed with the waste of calcined kaolin reacting at 90 deg C for 20 hours in an alkaline medium, in the presence of an additional source of silica was obtained zeolite Y as single phase present in the product. (author)

Assessment of the role of micropore size and N-doping in CO2 capture by porous carbons.

Science.gov (United States)

Sevilla, Marta; Parra, Jose B; Fuertes, Antonio B

2013-07-10

The role of micropore size and N-doping in CO2 capture by microporous carbons has been investigated by analyzing the CO2 adsorption properties of two types of activated carbons with analogous textural properties: (a) N-free carbon microspheres and (b) N-doped carbon microspheres. Both materials exhibit a porosity made up exclusively of micropores ranging in size between micropores with a size below 0.8 nm. It was also observed that the CO2 capture capacities of undoped and N-doped carbons are analogous which shows that the nitrogen functionalities present in these N-doped samples do not influence CO2 adsorption. Taking into account the temperature invariance of the characteristic curve postulated by the Dubinin theory, we show that CO2 uptakes can be accurately predicted by using the adsorption data measured at just one temperature.

Parallel recognition of cancer cells using an addressable array of solid-state micropores.

Science.gov (United States)

Ilyas, Azhar; Asghar, Waseem; Kim, Young-tae; Iqbal, Samir M

2014-12-15

Early stage detection and precise quantification of circulating tumor cells (CTCs) in the peripheral blood of cancer patients are important for early diagnosis. Early diagnosis improves the effectiveness of the therapy and results in better prognosis. Several techniques have been used for CTC detection but are limited by their need for dye tagging, low throughput and lack of statistical reliability at single cell level. Solid-state micropores can characterize each cell in a sample providing interesting information about cellular populations. We report a multi-channel device which utilized solid-state micropores array assembly for simultaneous measurement of cell translocation. This increased the throughput of measurement and as the cells passed the micropores, tumor cells showed distinctive current blockade pulses, when compared to leukocytes. The ionic current across each micropore channel was continuously monitored and recorded. The measurement system not only increased throughput but also provided on-chip cross-relation. The whole blood was lysed to get rid of red blood cells, so the blood dilution was not needed. The approach facilitated faster processing of blood samples with tumor cell detection efficiency of about 70%. The design provided a simple and inexpensive method for rapid and reliable detection of tumor cells without any cell staining or surface functionalization. The device can also be used for high throughput electrophysiological analysis of other cell types. Copyright © 2014 Elsevier B.V. All rights reserved.

Microporous-mesoporous carbons for energy storage synthesized by activation of carbonaceous material by zinc chloride, potassium hydroxide or mixture of them

Science.gov (United States)

Härmas, M.; Thomberg, T.; Kurig, H.; Romann, T.; Jänes, A.; Lust, E.

2016-09-01

Various electrochemical methods have been applied to establish the electrochemical characteristics of the electrical double layer capacitor (EDLC) consisting of the 1 M triethylmethylammonium tetrafluoroborate solution in acetonitrile and activated carbon based electrodes. Activated microporous carbon materials used for the preparation of electrodes have been synthesized from the hydrothermal carbonization product (HTC) prepared via hydrothermal carbonization process of D-(+)-glucose solution in H2O, followed by activation with ZnCl2, KOH or their mixture. Highest porosity and Brunauer-Emmett-Teller specific surface area (SBET = 2150 m2 g-1), micropore surface area (Smicro = 2140 m2 g-1) and total pore volume (Vtot = 1.01 cm3 g-1) have been achieved for HTC activated using KOH with a mass ratio of 1:4 at 700 °C. The correlations between SBET, Smicro, Vtot and electrochemical characteristics have been studied to investigate the reasons for strong dependence of electrochemical characteristics on the synthesis conditions of carbon materials studied. Wide region of ideal polarizability (ΔV ≤ 3.0 V), very short characteristic relaxation time (0.66 s), and high specific series capacitance (134 F g-1) have been calculated for the mentioned activated carbon material, demonstrating that this system can be used for completing the EDLC with high energy- and power densities.

Sulfur rich microporous polymer enables rapid and efficient removal of mercury(II) from water.

Science.gov (United States)

Xu, Dan; Wu, Winston Duo; Qi, Hao-Jun; Yang, Rui-Xia; Deng, Wei-Qiao

2018-04-01

Design and synthesis of adsorbents for efficient decontamination of hazardous contaminants Hg 2+ from wastewater, based on a facile and economical strategy, is an attractive target. Here, a novel sulfur rich microporous polymer (sulfur content of 31.4 wt %) with high surface area as well as densely populated sulfur atom with fast accessibility was reported to remove mercury (II) from water. The as prepared polymer (SMP) exhibited high binding affinity, high adsorption capacities, rapid adsorption kinetics, and good recyclability for Hg 2+ . The adsorption capacity of SMP was 595.2 mg g -1 . Furthermore, SMP could reduce trace concentrations of Hg 2+ from 200 p. p. b. to a level below drinking water standards (2 p. p. b.) within 3 min. This work allows large-scale production of sulfur rich porous materials for the practical application in water treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Study on preparation of laser micropore porcine acellular dermal matrix combined with split-thickness autograft and its application in wound transplantation].

Science.gov (United States)

Liang, Li-Ming; Chai, Ji-Ke; Yang, Hong-Ming; Feng, Rui; Yin, Hui-Nan; Li, Feng-Yu; Sun, Qiang

2007-04-01

To prepare a porcine acellular dermal matrix (PADM), and to optimize the interpore distance between PADM and co-grafted split-thickness autologous skin. Porcine skin was treated with trypsin/Triton X-100 to prepare an acellular dermal matrix. Micropores were produced on the PADM with a laser punch. The distance between micropores varied as 0.8 mm, 1.0 mm, 1.2 mm and 1.5 mm. Full-thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into 6 groups as follows, with 24 rats in each group. Micropore groups I -IV: the wounds were grafted with PADM with micropores in four different intervals respectively, and covered with split-thickness autologous skin graft. Mesh group: the wounds were grafted with meshed PADM and split-thickness autograft. with simple split-thickness autografting. The gross observation of wound healing and histological observation were performed at 2, 4, 6 weeks after surgery. The wound healing rate and contraction rate were calculated. Two and four weeks after surgery, the wound healing rate in micropore groups I and II was lower than that in control group (P micropore groups I , II and mesh group (P > 0.05) until 6 weeks after grafting( P micropore groups I and II ([(16.0 +/- 2.6)%, (15.1 +/- 2.4)%] was remarkably lower than that in control group 4 and 6 weeks after grafting (P micropore PADM (0.8 mm or 1.0 mm in distance) grafting in combination with split-thickness autografting can improve the quality of wound healing. PADM with laser micropores in 1.0 mm distance is the best choice among them.

Formation of a silicon micropore array of a two-dimension electron multiplier by photo electrochemical etching

International Nuclear Information System (INIS)

Gao Yanjun; Duanmu Qingduo; Wang Guozheng; Li Ye; Tian Jingquan

2009-01-01

A semiconductor PEC etching method is applied to fabricate the n-type silicon deep micropore channel array. In this method, it is important to arrange the direction of the micropore array along the crystal orientation of the Si substrate. Otherwise, serious lateral erosion will happen. The etching process is also relative to the light intensity and HF concentration. 5% HF concentration and 10-15 cm distance between the light source and the silicon wafer are demonstrated to be the best in our experiments. The n-type silicon deep micropore channel array with aperture of 3 μm and aspect ratio of 40-60, whose inner walls are smooth, is finally obtained.

Small-angle neutron scattering study of micropore collapse in amorphous solid water.

Science.gov (United States)

Mitterdorfer, Christian; Bauer, Marion; Youngs, Tristan G A; Bowron, Daniel T; Hill, Catherine R; Fraser, Helen J; Finney, John L; Loerting, Thomas

2014-08-14

Vapor-deposited amorphous solid water (ASW) is the most abundant solid molecular material in space, where it plays a direct role in both the formation of more complex chemical species and the aggregation of icy materials in the earliest stages of planet formation. Nevertheless, some of its low temperature physics such as the collapse of the micropore network upon heating are still far from being understood. Here we characterize the nature of the micropores and their collapse using neutron scattering of gram-quantities of D2O-ASW of internal surface areas up to 230 ± 10 m(2) g(-1) prepared at 77 K. The model-free interpretation of the small-angle scattering data suggests micropores, which remain stable up to 120-140 K and then experience a sudden collapse. The exact onset temperature to pore collapse depends on the type of flow conditions employed in the preparation of ASW and, thus, the specific surface area of the initial deposit, whereas the onset of crystallization to cubic ice is unaffected by the flow conditions. Analysis of the small-angle neutron scattering signal using the Guinier-Porod model suggests that a sudden transition from three-dimensional cylindrical pores with 15 Å radius of gyration to two-dimensional lamellae is the mechanism underlying the pore collapse. The rather high temperature of about 120-140 K of micropore collapse and the 3D-to-2D type of the transition unraveled in this study have implications for our understanding of the processing and evolution of ices in various astrophysical environments.

[Measurement and analysis of micropore aeration system's oxygenating ability under operation condition in waste water treatment plant].

Science.gov (United States)

Wu, Yuan-Yuan; Zhou, Xiao-Hong; Shi, Han-Chang; Qiu, Yong

2013-01-01

Using the aeration pool in the fourth-stage at Wuxi Lucun Waste Water Treatment Plant (WWTP) as experimental setup, off-gas method was selected to measure the oxygenating ability parameters of micropore aerators in a real WWTP operating condition and these values were compared with those in fresh water to evaluate the performance of the micropore aerators. Results showed that the micropore aerators which were distributed in different galleries of the aeration pool had significantly different oxygenating abilities under operation condition. The oxygenating ability of the micropore aerators distributed in the same gallery changed slightly during one day. Comparing with the oxygenating ability in fresh water, it decreased a lot in the real aeration pool, in more details, under the real WWTP operating condition, the values of oxygen transfer coefficient K(La) oxygenation capacity OC and oxygen utilization E(a) decreased by 43%, 57% and 76%, respectively.

129Xe NMR spectroscopy in microporous solids: The effect of bulk properties

International Nuclear Information System (INIS)

Ripmeester, John A.; Ratcliffe, Christopher I.

1993-01-01

In this contribution we point out a number of factors related to the bulk properties of microporous solids which must be taken into account in order first of all to obtain meaningful 129 Xe NMR spectral data, and secondly to interpret the data properly. This sensitivity to bulk properties is especially important for microporous solids where there is little or no barrier to xenon passage from inside the particle to the interparticle space. We examine the effect of particle size, powder bulk density and particle anisotropy, and also the effect of low thermal conductivity of low density powders

Hyper-parallel tempering Monte Carlo simulations of Ar adsorption in new models of microporous non-graphitizing activated carbon: effect of microporosity

International Nuclear Information System (INIS)

Terzyk, Artur P; Furmaniak, Sylwester; Gauden, Piotr A; Harris, Peter J F; Wloch, Jerzy; Kowalczyk, Piotr

2007-01-01

The adsorption of gases on microporous carbons is still poorly understood, partly because the structure of these carbons is not well known. Here, a model of microporous carbons based on fullerene-like fragments is used as the basis for a theoretical study of Ar adsorption on carbon. First, a simulation box was constructed, containing a plausible arrangement of carbon fragments. Next, using a new Monte Carlo simulation algorithm, two types of carbon fragments were gradually placed into the initial structure to increase its microporosity. Thirty six different microporous carbon structures were generated in this way. Using the method proposed recently by Bhattacharya and Gubbins (BG), the micropore size distributions of the obtained carbon models and the average micropore diameters were calculated. For ten chosen structures, Ar adsorption isotherms (87 K) were simulated via the hyper-parallel tempering Monte Carlo simulation method. The isotherms obtained in this way were described by widely applied methods of microporous carbon characterisation, i.e. Nguyen and Do, Horvath-Kawazoe, high-resolution α s plots, adsorption potential distributions and the Dubinin-Astakhov (DA) equation. From simulated isotherms described by the DA equation, the average micropore diameters were calculated using empirical relationships proposed by different authors and they were compared with those from the BG method

Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

Science.gov (United States)

Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

2009-05-01

Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

Anisotropic microporous supports impregnated with polymeric ion-exchange materials

Science.gov (United States)

Friesen, Dwayne; Babcock, Walter C.; Tuttle, Mark

1985-05-07

Novel ion-exchange media are disclosed, the media comprising polymeric anisotropic microporous supports containing polymeric ion-exchange or ion-complexing materials. The supports are anisotropic, having small exterior pores and larger interior pores, and are preferably in the form of beads, fibers and sheets.

Effects of drying time on the surface morphology evolution of urushiol-formaldehyde diethylenetriamine polymer microporous films

International Nuclear Information System (INIS)

Xu Yanlian; Bai Weibin; Luo Zhen; Jin Yao; Peng Bichen; Feng Lixia; Hu Binghuan; Lin Jinhuo

2012-01-01

Raw lacquer, a renewable and eco-friendly biopolymer material with excellent physico-mechanical properties, has been principally used to coat objects of high artistic and pleasing beauty for centuries. In previous reports, we studied microporous urushiol-based polymer (UBP) films by the water-assisted assembly method. The effect of drying time on the formation of breath figures with honeycomb patterns in the microporous films of urushiol-formaldehyde diethylenetriamine polymer (UFDP) was investigated in this paper. The pattern structure was studied with optical microscopy (OM) and scanning electron microscopy (SEM). The drying time, which is influenced by the reflux time, plays a decisive role in the morphology, such as pore size and distribution periodicity, of the microporous UFDP films.

Effects of drying time on the surface morphology evolution of urushiol-formaldehyde diethylenetriamine polymer microporous films

Energy Technology Data Exchange (ETDEWEB)

Xu Yanlian, E-mail: ylxu@fjnu.edu.cn [College of Chemistry and Materials, Fujian Normal University, Fuzhou 350007 (China); Fujian Key Laboratory of Polymer Materials, Fuzhou 350007 (China); Bai Weibin; Luo Zhen; Jin Yao; Peng Bichen; Feng Lixia [College of Chemistry and Materials, Fujian Normal University, Fuzhou 350007 (China); Hu Binghuan [Fujian Key Laboratory of Polymer Materials, Fuzhou 350007 (China); Lin Jinhuo, E-mail: jhlin@fjnu.edu.cn [College of Chemistry and Materials, Fujian Normal University, Fuzhou 350007 (China); Fujian Key Laboratory of Polymer Materials, Fuzhou 350007 (China)

2012-04-01

Raw lacquer, a renewable and eco-friendly biopolymer material with excellent physico-mechanical properties, has been principally used to coat objects of high artistic and pleasing beauty for centuries. In previous reports, we studied microporous urushiol-based polymer (UBP) films by the water-assisted assembly method. The effect of drying time on the formation of breath figures with honeycomb patterns in the microporous films of urushiol-formaldehyde diethylenetriamine polymer (UFDP) was investigated in this paper. The pattern structure was studied with optical microscopy (OM) and scanning electron microscopy (SEM). The drying time, which is influenced by the reflux time, plays a decisive role in the morphology, such as pore size and distribution periodicity, of the microporous UFDP films.

Sorption and leaching properties of the composites and humic complexes of natural microporous materials

International Nuclear Information System (INIS)

Masasek, F.

1998-01-01

This contribution deals with scientific basis and engineering practices of natural microporous materials (NMM) which are projected for a millennia horizon of the environmental protection. Microcrystalline structure of inorganic microporous sorbents is discussed. Artificial formation composites and both inorganic and organic complexes of NMM is applied for> (1) field barriers, fills or supporting structures, (2) reagents and organic coating supports, (3) granules, pellets and column packings, (4) additives to cementitious fixation matrices, and (4) glass formulations

High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

Energy Technology Data Exchange (ETDEWEB)

Kumar, Arvind; Mohan Jena, Hara, E-mail: hmjena@nitrkl.ac.in

2015-11-30

Graphical abstract: - Highlights: • Activated carbons have been prepared from Fox nutshell with chemical activation using ZnCl{sub 2}. • The thermal behavior of the raw material and impregnated raw material has been carried out by thermogravimetric analysis. • The characterizations of the prepared activated carbons have been determined by nitrogen adsorption–desorption isotherms, FTIR, XRD, and FESEM. • The BET surface area and total pore volume of prepared activated carbon has been obtained as 2869 m{sup 2}/g, 2124 m{sup 2}/g, and 1.96 cm{sup 3}/g, respectively. • The microporous surface area, micropore volume, and microporosity percentage of prepared activated carbon has been obtained as 2124 m{sup 2}/g, 1.68 cm{sup 3}/g, and 85.71%, respectively. - Abstract: High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl{sub 2} as an activator. The process has been conducted at different impregnation (ZnCl{sub 2}/Fox nutshell) ratios (1–2.5) and carbonization temperatures (500–700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption–desorption isotherms at −196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m{sup 2}/g, 2124 m{sup 2}/g, 1.96 cm{sup 3}/g, and 1.68 cm{sup 3}/g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

International Nuclear Information System (INIS)

Kumar, Arvind; Mohan Jena, Hara

2015-01-01

Graphical abstract: - Highlights: • Activated carbons have been prepared from Fox nutshell with chemical activation using ZnCl 2 . • The thermal behavior of the raw material and impregnated raw material has been carried out by thermogravimetric analysis. • The characterizations of the prepared activated carbons have been determined by nitrogen adsorption–desorption isotherms, FTIR, XRD, and FESEM. • The BET surface area and total pore volume of prepared activated carbon has been obtained as 2869 m 2 /g, 2124 m 2 /g, and 1.96 cm 3 /g, respectively. • The microporous surface area, micropore volume, and microporosity percentage of prepared activated carbon has been obtained as 2124 m 2 /g, 1.68 cm 3 /g, and 85.71%, respectively. - Abstract: High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl 2 as an activator. The process has been conducted at different impregnation (ZnCl 2 /Fox nutshell) ratios (1–2.5) and carbonization temperatures (500–700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption–desorption isotherms at −196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m 2 /g, 2124 m 2 /g, 1.96 cm 3 /g, and 1.68 cm 3 /g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

Microporous dermal-mimetic electrospun scaffolds pre-seeded with fibroblasts promote tissue regeneration in full-thickness skin wounds.

Directory of Open Access Journals (Sweden)

Paul P Bonvallet

Full Text Available Electrospun scaffolds serve as promising substrates for tissue repair due to their nanofibrous architecture and amenability to tailoring of chemical composition. In this study, the regenerative potential of a microporous electrospun scaffold pre-seeded with dermal fibroblasts was evaluated. Previously we reported that a 70% collagen I and 30% poly(Ɛ-caprolactone electrospun scaffold (70:30 col/PCL containing 160 μm diameter pores had favorable mechanical properties, supported fibroblast infiltration and subsequent cell-mediated deposition of extracellular matrix (ECM, and promoted more rapid and effective in vivo skin regeneration when compared to scaffolds lacking micropores. In the current study we tested the hypothesis that the efficacy of the 70:30 col/PCL microporous scaffolds could be further enhanced by seeding scaffolds with dermal fibroblasts prior to implantation into skin wounds. To address this hypothesis, a Fischer 344 (F344 rat syngeneic model was employed. In vitro studies showed that dermal fibroblasts isolated from F344 rat skin were able to adhere and proliferate on 70:30 col/PCL microporous scaffolds, and the cells also filled the 160 μm pores with native ECM proteins such as collagen I and fibronectin. Additionally, scaffolds seeded with F344 fibroblasts exhibited a low rate of contraction (~14% over a 21 day time frame. To assess regenerative potential, scaffolds with or without seeded F344 dermal fibroblasts were implanted into full thickness, critical size defects created in F344 hosts. Specifically, we compared: microporous scaffolds containing fibroblasts seeded for 4 days; scaffolds containing fibroblasts seeded for only 1 day; acellular microporous scaffolds; and a sham wound (no scaffold. Scaffolds containing fibroblasts seeded for 4 days had the best response of all treatment groups with respect to accelerated wound healing, a more normal-appearing dermal matrix structure, and hair follicle regeneration

Fabrication of microporous polymethacrylimide using γ-rays irradiation and characterization of its properties

International Nuclear Information System (INIS)

Tang Jianjun; Xu Yunshu; Xiong Liangping; Gao Xiaoling; Xu Guangliang

2011-01-01

Methylacrylic acid (MAA), acrylonitrile (AN), acrylamide (AM) and methyl methacrylate (MMA) were polymerized by γ-rays, and AN/AM/MAA copolymer as well as polymethylmethacrylate (PMMA) were synthesized. Then microporous structure of polymethacrylimide (PMI) was obtained by the degradation of PMMA using heat-treatment. FIR spectra showed that imide process and PMMA degradation were simultaneous at the selected temperature. TG-DSC analysis showed that the sample began to degrade at 345 degree C. And SEM indicated that microporous PMI with obturator foramen structure was obtained, whose aperture was about 100 μm. (authors)

Organic Microporous Nanofillers with Unique Alcohol Affinity for Superior Ethanol Recovery toward Sustainable Biofuels.

Science.gov (United States)

Cheng, Xi Quan; Konstas, Kristina; Doherty, Cara M; Wood, Colin D; Mulet, Xavier; Xie, Zongli; Ng, Derrick; Hill, Matthew R; Lau, Cher Hon; Shao, Lu

2017-05-09

To minimize energy consumption and carbon footprints, pervaporation membranes are fast becoming the preferred technology for alcohol recovery. However, this approach is confined to small-scale operations, as the flux of standard rubbery polymer membranes remain insufficient to process large solvent volumes, whereas membrane separations that use glassy polymer membranes are prone to physical aging. This study concerns how the alcohol affinity and intrinsic porosity of networked, organic, microporous polymers can simultaneously reduce physical aging and drastically enhance both flux and selectivity of a super glassy polymer, poly-[1-(trimethylsilyl)propyne] (PTMSP). Slight loss in alcohol transportation channels in PTMSP is compensated by the alcohol affinity of the microporous polymers. Even after continuous exposure to aqueous solutions of alcohols, PTMSP pervaporation membranes loaded with the microporous polymers outperform the state-of-the-art and commercial pervaporation membranes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen adsorption in microporous alkali-doped carbons (single-wall carbon nano-tubes and activated carbons)

International Nuclear Information System (INIS)

Laurent Duclaux; Szymon Los; Michel Letellier; Philippe Azais; Roland Pellenq; Thomas Roussel; Xavier Fuhr

2006-01-01

Doping of microporous carbon by Li or K leads to an increase in the energy of adsorption of H 2 or D 2 molecules. Thus, the room temperature sorption capacities (at P≤3 MPa) can be higher than the ones of the raw materials after slight doping. However, the maximum H 2 (or D 2 ) storage uptake measured at T≤ 77 K is lower than the one of pristine materials as the sites of adsorption are occupied by alkali ions inserted in the micropores. The microporous adsorption sites of doped single-walled carbon nano-tubes, identified by neutron diffraction, are both the interstitial voids (in electric-arc or HiPCO tubes) in between the tubes and the central canals of the tubes (only in HiPCO tubes). (authors)

Unusual Coordination Behavior of Cr3+ in Microporous Aluminophosphates

NARCIS (Netherlands)

Beale, AM; Grandjean, D; Kornatowski, J; Glatzel, P; de Groot, FMF; Weckhuysen, BM

2006-01-01

A CrAPO-5 molecular sieve has been investigated with X-ray absorption spectroscopy (EXAFS-XANES) as dehydrated material and after loading with water and ammonia to unravel the coordination geometries of Cr3+ in the framework of a microporous crystalline aluminophosphate, more particularly of the

Influence of Micropore and Mesoporous in Activated Carbon Air-cathode Catalysts on Oxygen Reduction Reaction in Microbial Fuel Cells

International Nuclear Information System (INIS)

Liu, Yi; Li, Kexun; Ge, Baochao; Pu, Liangtao; Liu, Ziqi

2016-01-01

In this study, carbon samples with different micropore and mesoporous structures are prepared as air-cathode catalyst layer to explore the role of pore structure on oxygen reduction reaction. The results of linear sweep voltammetry and power density show that the commercially-produced activated carbon (CAC) has the best electrochemical performance, and carbon samples with only micropore or mesoporous show lower performance than CAC. Nitrogen adsorption-desorption isotherms analysis confirm that CAC has highest surface area (1616 m 2 g −1 ) and a certain amount of micropore and mesoporous. According to Tafel plot and rotating disk electrode, CAC behaves the highest kinetic activity and electron transfer number, leading to the improvement of oxygen reduction reaction. The air permeability test proves that mesoporous structure enhance oxygen permeation. Carbon materials are also analyzed by In situ Fourier Transform Infrared Spectroscopy and H 2 temperature programmed reduction, which indicate that micropore provide active sites for catalysis. In a word, micropore and mesoporous together would improve the electrochemical performance of carbon materials.

Development and evaluation of microporous osmotic tablets of diltiazem hydrochloride

Directory of Open Access Journals (Sweden)

Afifa Bathool

2012-01-01

Full Text Available Microporous osmotic tablet of diltiazem hydrochloride was developed for colon targeting. These prepared microporous osmotic pump tablet did not require laser drilling to deliver the drug to the specific site of action. The tablets were prepared by wet granulation method. The prepared tablets were coated with microporous semipermeable membrane and enteric polymer using conventional pan coating process. The incorporation of sodium lauryl sulfate (SLS, a leachable pore-forming agent, could form in situ delivery pores while coming in contact with gastrointestinal medium. The effect of formulation variables was studied by changing the amounts of sodium alginate and NaCMC in the tablet core, osmogen, and that of pore-forming agent (SLS used in the semipermeable coating. As the amount of hydrophilic polymers increased, drug release rate prolonged. It was found that drug release was increased as the concentration of osmogen and pore-former was increased. Fourier transform infrared spectroscopy and Differential scanning calorimetry results showed that there was no interaction between drug and polymers. Scanning electron microscopic studies showed the formation of pores after predetermined time of coming in contact with dissolution medium. The formation of pores was dependent on the amount of pore former used in the semipermeable membrane. in vitro results showed acid-resistant, timed release at an almost zero order up to 24 hours. The developed osmotic tablets could be effectively used for prolonged delivery of Diltiazem HCl.

Morphology and characterization of 3D micro-porous structured chitosan scaffolds for tissue engineering.

Science.gov (United States)

Hsieh, Wen-Chuan; Chang, Chih-Pong; Lin, Shang-Ming

2007-06-15

This research studies the morphology and characterization of three-dimensional (3D) micro-porous structures produced from biodegradable chitosan for use as scaffolds for cells culture. The chitosan 3D micro-porous structures were produced by a simple liquid hardening method, which includes the processes of foaming by mechanical stirring without any chemical foaming agent added, and hardening by NaOH cross linking. The pore size and porosity were controlled with mechanical stirring strength. This study includes the morphology of chitosan scaffolds, the characterization of mechanical properties, water absorption properties and in vitro enzymatic degradation of the 3D micro-porous structures. The results show that chitosan 3D micro-porous structures were successfully produced. Better formation samples were obtained when chitosan concentration is at 1-3%, and concentration of NaOH is at 5%. Faster stirring rate would produce samples of smaller pore diameter, but when rotation speed reaches 4000 rpm and higher the changes in pore size is minimal. Water absorption would reduce along with the decrease of chitosan scaffolds' pore diameter. From stress-strain analysis, chitosan scaffolds' mechanical properties are improved when it has smaller pore diameter. From in vitro enzymatic degradation results, it shows that the disintegration rate of chitosan scaffolds would increase along with the processing time increase, but approaching equilibrium when the disintegration rate reaches about 20%.

Microporous nano-MgO/diatomite ceramic membrane with high positive surface charge for tetracycline removal.

Science.gov (United States)

Meng, Xian; Liu, Zhimeng; Deng, Cheng; Zhu, Mengfu; Wang, Deyin; Li, Kui; Deng, Yu; Jiang, Mingming

2016-12-15

A novel microporous nano-MgO/diatomite ceramic membrane with high positive surface charge was prepared, including synthesis of precursor colloid, dip-coating and thermal decomposition. Combined SEM, EDS, XRD and XPS studies show the nano-MgO is irregularly distributed on the membrane surface or pore walls and forms a positively charged nano coating. And the nano-MgO coating is firmly attached to the diatomite membrane via SiO chemical bond. Thus the nano-MgO/diatomite membrane behaves strong electropositivity with the isoelectric point of 10.8. Preliminary filtration tests indicate that the as-prepared nano-MgO/diatomite membrane could remove approximately 99.7% of tetracycline in water through electrostatic adsorption effect. The desirable electrostatic property enables the nano-MgO/diatomite membrane to be a candidate for removal of organic pollutants from water. And it is convinced that there will be a great application prospect of charged ceramic membrane in water treatment field. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct fabrication of ordered mesoporous carbons with super-micropore/small mesopore using mixed triblock copolymers.

Science.gov (United States)

Li, Peng; Song, Yan; Tang, Zhihong; Yang, Guangzhi; Yang, Junhe

2014-01-01

Ordered mesoporous carbons (OMCs) have been prepared by the strategy of evaporation-induced organic-organic self-assembly method by employing a mixture of amphiphilic triblock copolymers poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) and reverse PPO-PEO-PPO as templates, with soluble in ethanol, low-molecular-weight phenolic resin as precursor, followed by carbonization. It has been found that the as prepared OMCs with porosity that combines super-micropore and small mesopore size distributed from 0.8 to 4 nm, which bridges the pore size from 2 to 3 nm and also for the diversification of the soft-templating synthesis of OMCs. Furthermore, the results showed that the OMCs obtained have mesophase transition from cylindrical p6 mm to centered rectangular c2 mm structure by simply tuning the ratio of PPO-PEO-PPO/PEO-PPO-PEO. Copyright © 2013 Elsevier Inc. All rights reserved.

Hydrothermal stability of microporous silica and niobia-silica membranes

NARCIS (Netherlands)

Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

2008-01-01

The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

Characterization of Microporous Insulation, Microsil

Energy Technology Data Exchange (ETDEWEB)

Thomas, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-06-15

Microsil microporous insulation has been characterized by Lawrence Livermore National Laboratory for possible use in structural and thermal applications in the DPP-1 design. Qualitative test results have provided mechanical behavioral characteristics for DPP-1 design studies and focused on the material behavioral response to being crushed, cyclically loaded, and subjected to vibration for a confined material with an interference fit or a radial gap. Quantitative test results have provided data to support the DPP-1 FEA model analysis and verification and were used to determine mechanical property values for the material under a compression load. The test results are documented within this report.

Sorption of phenanthrene and benzene on differently structural kerogen: important role of micropore-filling.

Science.gov (United States)

Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

2014-02-01

Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23-46% and 36-65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Numerical investigation of micro-pore formation during substrate impact of molten droplets in spraying processes

International Nuclear Information System (INIS)

Liu, H.; Lavernia, E.J.; Rangel, R.H.; Muehlberger, E.; Sickinger, A.

1994-01-01

The porosity that is commonly associated with discrete droplet processes, such as plasma spraying and spray deposition, effectively degrades the quality of the sprayed material. In the present study, micro-pore formation during the deformation and interaction of molten tungsten droplets impinging onto a flat substrate in spraying processes is numerically investigated. The numerical simulation is accomplished on the basis of the full Navier-Stokes equations and the Volume Of Fluid (VOF) function by using a 2-domain method for the thermal field and solidification problem and a two-phase flow continuum model for the flow problem with a growing solid layer. The possible mechanisms governing the formation of micro-pores are discussed. The effects of important processing parameters, such as droplet impact velocity, droplet temperature, substrate temperature, and droplet viscosity, on the micro-pore formation are addressed

Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

Science.gov (United States)

Lv, Jinze; Zhu, Lizhong

2013-01-01

A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

Hierarchical zeolites: Enhanced utilisation of microporous crystals in catalysis by advances in materials design

DEFF Research Database (Denmark)

Perez-Ramirez, Javier; Christensen, Claus H.; Egeblad, Kresten

2008-01-01

The introduction of synthetic zeolites has led to a paradigm shift in catalysis, separations, and adsorption processes, due to their unique properties such as crystallinity, high-surface area, acidity, ion-exchange capacity, and shape-selective character. However, the sole presence of micropores...... the properties of the resulting materials and the catalytic function. We particularly dwell on the exciting field of hierarchical zeolites, which couple in a single material the catalytic power of micropores and the facilitated access and improved transport consequence of a complementary mesopore network...

Pool boiling characteristics and critical heat flux mechanisms of microporous surfaces and enhancement through structural modification

Science.gov (United States)

Ha, Minseok; Graham, Samuel

2017-08-01

Experimental studies have shown that microporous surfaces induce one of the highest enhancements in critical heat flux (CHF) during pool boiling. However, microporous surfaces may also induce a very large surface superheat (>100 °C) which is not desirable for applications such as microelectronics cooling. While the understanding of the CHF mechanism is the key to enhancing boiling heat transfer, a comprehensive understanding is not yet available. So far, three different theories for the CHF of microporous surfaces have been suggested: viscous-capillary model, hydrodynamic instability model, and dryout of the porous coatings. In general, all three theories account for some aspects of boiling phenomena. In this study, the theories are examined through their correlations with experimental data on microporous surfaces during pool boiling using deionized (DI) water. It was found that the modulation of the vapor-jet through the pore network enables a higher CHF than that of a flat surface based on the hydrodynamic instability theory. In addition, it was found that as the heat flux increases, a vapor layer grows in the porous coatings described by a simple thermal resistance model which is responsible for the large surface superheat. Once the vapor layer grows to fill the microporous structure, transition to film boiling occurs and CHF is reached. By disrupting the formation of this vapor layer through the fabrication of channels to allow vapor escape, an enhancement in the CHF and heat transfer coefficient was observed, allowing CHF greater than 3500 kW/m2 at a superheat less than 50 °C.

Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling

International Nuclear Information System (INIS)

Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

2014-01-01

Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (V o,d ) initially increase and then decrease. The V o,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The V o,d of phenanthrene and benzene on the kerogen samples accounts for 23–46% and 36–65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling. -- Highlights: • The microporosity estimated by benzene vapor differs greatly from that by N 2 . • The micropore volume changes with kerogen maturation. • The phenanthrene or benzene sorption is related to the microporosity of kerogen. • Higher adsorption volume for benzene than for phenanthrene suggests molecular sieve effect. • The pore-filling plays an important role in the sorption of phenanthrene and benzene. -- The sorption behaviors of benzene and phenanthrene are related to the microporosity of the differently matured kerogen, indicating the importance of pore-filling

Fractional ablative erbium YAG laser: histological characterization of relationships between laser settings and micropore dimensions.

Science.gov (United States)

Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M; Philipsen, Peter A; Anderson, R Rox; Paasch, Uwe; Haedersdal, Merete

2014-04-01

Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating laser parameters with tissue effects. Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15-2.22 W, pulse durations 50-225 microseconds, pulse repetition rates 100-500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse energies of 2.3-12.8 mJ/microbeam and total energy levels of 4.6-640 mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints were combined in a mathematical model. In 138 sections from 91 biopsies, AD ranged from 16 to a maximum of 1,348 µm and increased linearly with the logarithm of total energy delivered by stacked pulses, but also depended on variations in power, pulse duration, pulse repetition rate, and pulse energy (r(2)  = 0.54-0.85, P micropores of specific ADs with an associated range of CZs and AWs, for example, 300 µm ADs were associated with CZs from 27 to 73 µm and AWs from 190 to 347 µm. Pulse stacking with a small, low power 2,940 nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser settings for desired tissue effects. © 2014 Wiley Periodicals, Inc.

Macroscale and microscale fracture toughness of microporous sintered Ag for applications in power electronic devices

International Nuclear Information System (INIS)

Chen, Chuantong; Nagao, Shijo; Suganuma, Katsuaki; Jiu, Jinting; Sugahara, Tohru; Zhang, Hao; Iwashige, Tomohito; Sugiura, Kazuhiko; Tsuruta, Kazuhiro

2017-01-01

The application of microporous sintered silver (Ag) as a bonding material to replace conventional die-bonding materials in power electronic devices has attracted considerable interest. Characterization of the mechanical properties of microporous Ag will enable its use in applications such as lead-free solder electronics and provide a fundamental understanding of its design principles. However, the material typically suffers from thermal and mechanical stress during its production fabrication, and service. In this work, we have studied the effect of microporous Ag specimen size on fracture toughness from the microscale to the macroscale. A focused ion beam was used to fabricate 20-, 10- and 5-μm-wide microscale specimens, which were of the same order of magnitude as the pore networks in the microporous Ag. Micro-cantilever bending tests revealed that fracture toughness decreased as the specimen size decreased. Conventional middle-cracked tensile tests were performed to determine the fracture toughness of the macroscale specimens. The microscale and macroscale fracture toughness results showed a clear size effect, which is discussed in terms of both the deformation behavior of crack tip and the influence of pore networks within Ag with different specimen sizes. Finite element model simulations showed that stress at the crack tip increased as the specimen size increased, which led to larger plastic deformation and more energy being consumed when the specimen fractured.

Synergistic effects of dendritic cell targeting and laser-microporation on enhancing epicutaneous skin vaccination efficacy.

Science.gov (United States)

Machado, Yoan; Duinkerken, Sanne; Hoepflinger, Veronika; Mayr, Melissa; Korotchenko, Evgeniia; Kurtaj, Almedina; Pablos, Isabel; Steiner, Markus; Stoecklinger, Angelika; Lübbers, Joyce; Schmid, Maximillian; Ritter, Uwe; Scheiblhofer, Sandra; Ablinger, Michael; Wally, Verena; Hochmann, Sarah; Raninger, Anna M; Strunk, Dirk; van Kooyk, Yvette; Thalhamer, Josef; Weiss, Richard

2017-11-28

Due to its unique immunological properties, the skin is an attractive target tissue for allergen-specific immunotherapy. In our current work, we combined a dendritic cell targeting approach with epicutaneous immunization using an ablative fractional laser to generate defined micropores in the upper layers of the skin. By coupling the major birch pollen allergen Bet v 1 to mannan from S. cerevisiae via mild periodate oxidation we generated hypoallergenic Bet-mannan neoglycoconjugates, which efficiently targeted CD14 + dendritic cells and Langerhans cells in human skin explants. Mannan conjugation resulted in sustained release from the skin and retention in secondary lymphoid organs, whereas unconjugated antigen showed fast renal clearance. In a mouse model, Bet-mannan neoglycoconjugates applied via laser-microporated skin synergistically elicited potent humoral and cellular immune responses, superior to intradermal injection. The induced antibody responses displayed IgE-blocking capacity, highlighting the therapeutic potential of the approach. Moreover, application via micropores, but not by intradermal injection, resulted in a mixed TH1/TH17-biased immune response. Our data clearly show that applying mannan-neoglycoconjugates to an organ rich in dendritic cells using laser-microporation is superior to intradermal injection. Due to their low IgE binding capacity and biodegradability, mannan neoglycoconjugates therefore represent an attractive formulation for allergen-specific epicutaneous immunotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

A compact process for the treatment of olive mill wastewater by combining wet hydrogen peroxide catalytic oxidation and biological techniques

International Nuclear Information System (INIS)

Azabou, Samia; Najjar, Wahiba; Bouaziz, Mohamed; Ghorbel, Abdelhamid; Sayadi, Sami

2010-01-01

A system based on combined actions of catalytic wet oxidation and microbial technologies for the treatment of highly polluted OMW containing polyphenols was studied. The wet hydrogen peroxide catalytic oxidation (WHPCO) process has been investigated in the semi-batch mode at atmospheric pressure, using aluminium-iron-pillared inter layer clay ((Al-Fe)PILC), under two different catalytic processes: ((Al-Fe)PILC/H 2 O 2 /ultraviolet radiations) at 25 deg. C and ((Al-Fe)PILC/H 2 O 2 ) at 50 deg. C. The results show that raw OMW was resistant to the photocatalytic process. However ((Al-Fe)PILC/H 2 O 2 ), system operating at 50 deg. C reduced considerably the COD, colour and total phenolic contents, and thus decreased the inhibition of the marine photobacteria Vibrio fischeri luminescence by 70%. This study also examined the feasibility of coupling WHPCO and anaerobic digestion treatment. Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H 2 O 2 ) system, for more than 2 h, resulted in higher methane production. Both untreated OMW as well as 2-h pre-treated OMW revealed as toxic to anaerobic bacteria.

The use of immersion calorimetry in the determination of micropore distribution of carbons in the course of activation

OpenAIRE

Kraehenbuehl, F.; Stoeckli, Fritz; Addoun, A.; Ehrburger, P.; Donnet, J. B.

2007-01-01

The combination of gas-solid adsorption experiments with immersion calorimetry of carbons into liquids of increasing molecular dimensions leads to accurate micropore distributions in the range 0.4-0.8 nm. This technique is used to study the development of the micropore structure during activation of carbons with CO2 or KOH.

Synthesis and characterization of V, Mo and Nb incorporated micro-mesoporous MCM-41 materials

Energy Technology Data Exchange (ETDEWEB)

Solmaz, Arzu, E-mail: arzu.solmaz@rshm.gov.tr [Gazi University, Faculty of Engineering, Chemical Engineering Department, 06570 Ankara (Turkey); Balci, Suna, E-mail: sunabalci@gazi.edu.tr [Gazi University, Faculty of Engineering, Chemical Engineering Department, 06570 Ankara (Turkey); Dogu, Timur, E-mail: tdogu@metu.edu.tr [Middle East Technical University, Faculty of Engineering, Chemical Engineering Department, 06531 Ankara (Turkey)

2011-01-01

Highly microporous metal-MCM-41 ordered mesoporous structure catalysts having different metal/Si (V, Mo, Nb) atomic ratios and combinations of metal sources were hydrothermally synthesized. The structural properties estimated using different techniques were found to be in agreement with each other. Metals were successfully incorporated into MCM-41 without deteriorating the ordered hexagonal structure. The metal ions in the synthesis solutions probably settled on the hydrophilic end of the template hence the metal incorporation resulted improvements in the micropore structure. Low loading of metals caused an increase in the surface area and pore volume values of the catalysts. The highest total (1310 m{sup 2} g{sup -1}) and micropore surface area values (1083 m{sup 2} g{sup -1}) were obtained by Nb incorporation. The micro- and mesopore dimensions of MCM-41 increased from 0.5 to 1.1 nm and from 2.5 to 2.8 nm, respectively, with metal incorporation. Low V/Si ratios and presence of Nb in the starting solution enhanced narrow mesopore size distribution. The pore dimension and wall thickness values estimated from nitrogen adsorption and X-ray diffraction methods were consistent with the corresponding values obtained using transmission electron microscopy.

Experimental study of air evaporative cooling process using microporous membranes

Directory of Open Access Journals (Sweden)

Englart Sebastian

2017-01-01

Full Text Available This article describes the potential use of microporous membranes in evaporative cooling applications for air conditioning. The structure of membrane contractor and the measuring device are described. On the basis of the results of the measurements air cooling effectiveness coefficient has been determined.

Microporous conjugated polymers via homopolymerization of 2,5-diethynylthiophene

Czech Academy of Sciences Publication Activity Database

Bondarev, D.; Sivkova, Radoslava; Šuly, P.; Polášková, M.; Krejčí, O.; Křikavová, R.; Trávníček, Z.; Zukal, Arnošt; Kubů, Martin; Sedláček, J.

2017-01-01

Roč. 92, July (2017), s. 213-219 ISSN 0014-3057 R&D Projects: GA ČR(CZ) GA15-09637S Institutional support: RVO:61389013 ; RVO:61388955 Keywords : thiophene * microporous * catalysis Subject RIV: CD - Macromolecular Chemistry; CD - Macromolecular Chemistry (UFCH-W) OBOR OECD: Polymer science; Polymer science (UFCH-W) Impact factor: 3.531, year: 2016

The movement of solutes through aqueous fissures in micro-porous rock during borehole experiments

International Nuclear Information System (INIS)

Glueckauf, E.

1981-02-01

When a tracer is injected for a short period into a solution flowing through a fissure in micro-porous rock, that tracer is not only carried along by the aqueous stream, but its local concentration is also markedly affected by hydro-dynamic dispersion and by sideway diffusion and adsorption in the micro-porous rock. The process has been simulated by computer calculations and these have made it possible to obtain from the concentration-time curves observed in borehole experiments an assessment of the physical parameters involving the water velocity and the hydro-dynamic dispersion in the fissure, and the diffusion and adsorption in the micro-porous rock. With these parameters it was then possible to recalculate quantitatively the local concentration-time history. However, in actual borehole experiments, the velocity of the water stream in the fissure is not known, and numerous side effects can distort the shape of the observed tracer curves. In order to test the theoretical interpretation more thoroughly, it is therefore proposed to carry out a laboratory experiment which simulates the borehole test under strictly defined conditions. (author)

Structure optimization of cathode microporous layer for direct methanol fuel cells

International Nuclear Information System (INIS)

Liu, Guicheng; Ding, Xianan; Zhou, Hongwei; Chen, Ming; Wang, Manxiang; Zhao, Zhenxuan; Yin, Zhuang; Wang, Xindong

2015-01-01

Highlights: • Pore-forming technology was introduced to optimize microporous layer microstructure. • The water removal and gas mass transfer property of diffusion layer were improved. • The optimum DMFC performance reached 292 mW cm −2 at 80 °C. - Abstract: To obtain the cathode microporous layer (CML) with high mass transfer performance and high electronic conductivity, a pore-forming technology was introduced to optimize CML microstructure for direct methanol fuel cells. In this paper, the effects of carbon material type, carbon material loading and pore-forming agent loading in CML on fuel cell performance were discussed systematically. The results indicated that the optimized CML consisted of carbon nanotubes and ammonium oxalate with the loading of 1.5 and 3.5 mg cm −2 respectively. The fuel cell performance was improved by 30.3%, from 224 to 292 mW cm −2 at 80 °C under 0.3 MPa O 2 . Carbon nanotube was found to be the most suitable carbon material for the CML due to its great specific surface area and small particle size, resulting in increasing the number of the hydrophobic sites and the contact area between the support and the catalyst layer. The carbon material and pore-forming agent loading directly influenced the pore distribution and the contact resistance of membrane electrode assembly. The water removal capacity and the gas mass transfer property of diffusion layer were improved by optimizing the amount of micropore and macropore structures

[Micropore filters for measuring red blood cell deformability and their pore diameters].

Science.gov (United States)

Niu, X; Yan, Z

2001-09-01

Micropore filters are the most important components in micropore filtration testes for assessing red blood cell (RBC) deformability. With regard to their appearance and filtration behaviors, comparisons are made for different kinds of filters currently in use. Nickel filters with regular geometric characteristics are found to be more sensitive to the effects of physical, chemical, especially pathological factors on the RBC deformability. We have critically reviewed the following viewpoint that filters with 3 microns pore diameter are more sensitive to cell volume than to internal viscosity while filters with 5 microns pore diameter are just the opposite. After analyzing the experiment results with 3 microns and 5 microns filters, we point out that filters with smaller pore diameters are more suitable for assessing the RBC deformability.

Selective removal of methyl mercaptan in coffee aroma using oxidized microporous carbon

Energy Technology Data Exchange (ETDEWEB)

Sakano, T. [Ajinomoto General Foods Inc., Tokyo (Japan). Central Research Laboratoties; Tamon, H.; Okazaki, M. [Kyoto University, Kyoto (Japan). Dept. of Chemical Engineering

1999-10-01

Coffee aroma recovered from the extraction process of roasted coffee beans is used to improve the quality of soluble coffee products. Coffee aroma often has an irritating sulfurous odor. In the present work, it is experimentally elucidated that methyl mercaptan could be selectively removed from the coffee aroma-containing gas by the oxidized microporous carbon. Breakthrough curves of coffee aroma-containing gas on zeolite 5A, microporous carbon (MSC 5A), and MSC 5A oxidized with 13.2N HNO{sub 3} aqueous solution revealed that the adsorption capacity of methyl mercaptan on the oxidized carbon was 4.2 times of that on the zeolite. The loss of desired coffee aroma was decreased using the oxidized carbon in the removal of methyl mercaptan. (author)

Freestanding, heat resistant microporous film for use in energy storage devices

Science.gov (United States)

Pekala, Richard W.; Cherukupalli, Srinivas; Waterhouse, Robert R.

2018-02-20

Preferred embodiments of a freestanding, heat resistant microporous polymer film (10) constructed for use in an energy storage device (70, 100) implements one or more of the following approaches to exhibit excellent high temperature mechanical and dimensional stability: incorporation into a porous polyolefin film of sufficiently high loading levels of inorganic or ceramic filler material (16) to maintain porosity (18) and achieve low thermal shrinkage; use of crosslinkable polyethylene to contribute to crosslinking the polymer matrix (14) in a highly inorganic material-filled polyolefin film; and heat treating or annealing of biaxially oriented, highly inorganic material-filled polyolefin film above the melting point temperature of the polymer matrix to reduce residual stress while maintaining high porosity. The freestanding, heat resistant microporous polymer film embodiments exhibit extremely low resistance, as evidenced by MacMullin numbers of less than 4.5.

Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al_3Ni_2@Al nanoparticles as a high microwave absorption material

International Nuclear Information System (INIS)

Pang, Yu; Xie, Xiubo; Li, Da; Chou, Wusheng; Liu, Tong

2017-01-01

The Al_3Ni_2@Al nanoparticles (NPs) were prepared from Ni_4_5Al_5_5 master alloy by hydrogen plasma-metal reaction method, and were subsequently dealloyed to produce porous Ni@NiO NPs of 36 nm. The pore size ranges from 0.7 to 1.6 nm, leading to large specific surface area of 69.5 m"2/g and big pore volume of 0.507 cc/g. The saturation magnetization (M_S) and coercivity (H_C) of the microporous Ni@NiO NPs are 11.5 emu/g and 5.2 Oe. They exhibit high microwave absorption performance with a minimum reflection coefficient (RC) of −86.9 dB and an absorption bandwidth of 2.6 GHz (RC≤−10 dB) at thickness of 4.5 mm. The enhanced microwave absorption properties are attributed to the synergistic effect of the magnetic Ni core and dielectric NiO shell, and the micropore architecture. The NPs with micropore morphology and core/shell structure open a new way to modify the microwave absorption performance. - Graphical abstract: The microporous Ni/NiO nanoparticles prepared by chemically dealloying Al_3Ni_2@Al NPs exhibit high microwave absorption intensity (−86.9 dB) and wide absorption bandwidth (2.6 GHz for RC≤−10 dB). - Highlights: • Microporous Ni/NiO nanoparticals were prepared by chemically dealloying method. • They possessed micropores of 0.7–1.6 nm with a surface area of 69.5 m"2/g. • They showed high microwave absorption intensity and wide absorption bandwidth. • Microwave absorption mechanism was explained by micropore and core/shell structures.

Straightforward Generation of Pillared, Microporous Graphene Frameworks for Use in Supercapacitors.

Science.gov (United States)

Yuan, Kai; Xu, Yazhou; Uihlein, Johannes; Brunklaus, Gunther; Shi, Lei; Heiderhoff, Ralf; Que, Mingming; Forster, Michael; Chassé, Thomas; Pichler, Thomas; Riedl, Thomas; Chen, Yiwang; Scherf, Ullrich

2015-11-01

Microporous, pillared graphene-based frameworks are generated in a simple functionalization/coupling procedure starting from reduced graphene oxide. They are used for the fabrication of high-performance supercapacitor devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Empleo de arcillas uruguayas pilareadas para el blanqueo de aceite de maiz.

Directory of Open Access Journals (Sweden)

Pagano, T.

1998-02-01

Full Text Available In the present paper adsorptive capacity to remove carotenes from a com oil by an Uruguayan montmorillonite modified by different treatments: exchange with Na⁺ ions (M-Na, acid-activation (Act, exchange with Ca²⁺ and pillaring with Keggin ions (Pile-Act, acid-activation and pillaring (Act Pil-Ca, is studied. Bleaching action of the Uruguayan modified montmorillonites is compared with two commercial days: Tonsil Optimum (Süd-Chemie and montmorillonite of type K 10 (Aldrich. Our results demonstrate that Act and Pilc-Ca samples are so efficient bleaching clays as commercials but M-Na sample Is lower. Also, mixtures of Pilc-Ca with commercial clays, added together in one step or consecutively in two steps, are studied. These procedures do not improved the bleaching action. As conclusion, the modified clay Pilc-Ca allows to bleach a neutralized and degummed corn oil, giving an end product similar to edible commercial oils. Such effect is improved with the simultaneous action with activated clays.

En este trabajo se estudia la capacidad de adsorción de los carotenos presentes en un aceite de maíz, de una montmorillonita uruguaya modificada por diferentes procedimientos: intercambiada con iones Na⁺ (M-Na, activada por ácido (Act, intercambiada con iones Ca²⁺ y pilareada con iones Keggin (Pilc-Ca, activada por ácidos y pilareada (Act Pilc-Ca frente a dos arcillas comerciales: Tonsil Optimum de Süd-Chemie y una Montmorillonita tipo K 10 de Aldrich. Los resultados indican que la muestra Act y la Pilc-Ca son tan eficientes como las comerciales pero que la capacidad de la muestra M-Na es considerablemente menor. También se efectuó ensayos con mezclas de Pilc-Ca con las arcillas comerciales, colocadas simultáneamente (en una sola etapa o agregadas de manera sucesiva (en dos etapas. Dichos procedimientos no mejoraron la eficiencia del blanqueo. En conclusión, la modificación Pilc-Ca permite

Influence of size, shape, and flexibility on bacterial passage through micropore membrane filters.

Science.gov (United States)

Wang, Yingying; Hammes, Frederik; Düggelin, Marcel; Egli, Thomas

2008-09-01

Sterilization of fluids by means of microfiltration is commonly applied in research laboratories as well as in pharmaceutical and industrial processes. Sterile micropore filters are subject to microbiological validation, where Brevundimonas diminuta is used as a standard test organism. However, several recent reports on the ubiquitous presence of filterable bacteria in aquatic environments have cast doubt on the accuracy and validity of the standard filter-testing method. Six different bacterial species of various sizes and shapes (Hylemonella gracilis, Escherichia coli, Sphingopyxis alaskensis, Vibrio cholerae, Legionella pneumophila, and B. diminuta) were tested for their filterability through sterile micropore filters. In all cases, the slender spirillum-shaped Hylemonella gracilis cells showed a superior ability to pass through sterile membrane filters. Our results provide solid evidence that the overall shape (including flexibility), instead of biovolume, is the determining factor for the filterability of bacteria, whereas cultivation conditions also play a crucial role. Furthermore, the filtration volume has a more important effect on the passage percentage in comparison with other technical variables tested (including flux and filter material). Based on our findings, we recommend a re-evaluation of the grading system for sterile filters, and suggest that the species Hylemonella should be considered as an alternative filter-testing organism for the quality assessment of micropore filters.

Fabrication of high-transmission microporous membranes by proton beam writing-based molding technique

Science.gov (United States)

Wang, Liping; Meyer, Clemens; Guibert, Edouard; Homsy, Alexandra; Whitlow, Harry J.

2017-08-01

Porous membranes are widely used as filters in a broad range of micro and nanofluidic applications, e.g. organelle sorters, permeable cell growth substrates, and plasma filtration. Conventional silicon fabrication approaches are not suitable for microporous membranes due to the low mechanical stability of thin film substrates. Other techniques like ion track etching are limited to the production of randomly distributed and randomly orientated pores with non-uniform pore sizes. In this project, we developed a procedure for fabricating high-transmission microporous membranes by proton beam writing (PBW) with a combination of spin-casting and soft lithography. In this approach, focused 2 MeV protons were used to lithographically write patterns consisting of hexagonal arrays of high-density pillars of few μm size in a SU-8 layer coated on a silicon wafer. After development, the pillars were conformably coated with a thin film of poly-para-xylylene (Parylene)-C release agent and spin-coated with polydimethylsiloxane (PDMS). To facilitate demolding, a special technique based on the use of a laser-cut sealing tape ring was developed. This method facilitated the successful delamination of 20-μm thick PDMS membrane with high-density micropores from the mold without rupture or damage.

Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation

Science.gov (United States)

Zeng, Zhirui; Tice, Michael M.

2018-01-01

Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms.

Biological function evaluation and effects of laser micro-pore burn-denatured acellular dermal matrix.

Science.gov (United States)

Zhang, Youlai; Zeng, Yuanlin; Xin, Guohua; Zou, Lijin; Ding, Yuewei; Duyin, Jiang

2018-03-01

In the field of burns repairs, many problems exist in the shortage of donor skin, the expense of allograft or xenograft skin, temporary substitution and unsatisfactory extremity function after wound healing. Previous studies showed that burn-denatured skin could return to normal dermis formation and function. This study investigates the application of laser micro-pore burn-denatured acellular dermis matrix (DADM) from an escharotomy in the repair of burn wounds and evaluates the biological properties and wound repair effects of DADM in implantation experiments in Kunming mice. Specific-pathogen-free (SPF) Kunming mice were used in this study. A deep II° burn wound was created on the dorsum of the mice by an electric heated water bath. The full-thickness wound tissue was harvested. The necrotic tissue and subcutaneous tissue were removed. The denatured dermis was preserved and treated with 0.25% trypsin, 0.5% Triton X-100. The DADM was drilled by laser micro-pore. The biological properties and grafting effects of laser micro-pore burn-DADM were evaluated by morphology, cytokine expression levels and subcutaneous implantation experiments in Kunming mice. We found statistical significance (Ppore burn-DADM (experimental group) compared to the control group (no laser micro-pore burn-DADM). Cytokine expression level was different in the dermal matrixes harvested at various time points after burn (24h, 48h, 72h and infected wound group). Comparing the dermal matrix from 24h burn tissue to infected wound tissue, the expression level of IL-6, MMP-24, VE-cadherin and VEGF were decreased. We found no inflammatory cells infiltration in the dermal matrix were observed in both experimental and control groups (24h burn group), while the obviously vascular infiltration and fiber fusion were observed in the experimental group after subcutaneous implantation experiments. There was better bio-performance, low immunogenicity and better dermal incorporation after treated by laser

Polymer-derived microporous ceramics for membranes and sensors for high temperature hydrogen purification and sensing

Energy Technology Data Exchange (ETDEWEB)

Prasad, Ravi Mohan

2012-06-11

The growing interest in the use of hydrogen as main fuel has increased the need for pure hydrogen (H{sub 2}) production and purification. There are several by-products (CO, H{sub 2}O, CO{sub 2}) associated with the production of hydrogen which might damage the production rate. Therefore, separation of hydrogen from other gases is an important step in the hydrogen production process. If H{sub 2} can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single-step under high temperature conditions. The main goal of the present work is the high temperature H{sub 2} purification and sensing by applying polymer-derived ceramics. To prove the concept, the microporous SiBCN, Si{sub 3}N{sub 4} and SiCN ceramic membranes have been synthesized by the polymer-pyrolysis route and their performance for the hydrogen separation have been evaluated in tubular membranes as well as in planar chemiresistors. The synthesis of amorphous SiBCN ceramics has been realized through pyrolysis of poly(organoborosilazanes) in argon. Multilayered amorphous SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membranes with gradient porosity have been realized and assessed with respect to the thermal stability, pore-size distribution and H{sub 2}/CO permeance. N{sub 2}-adsorption measurement indicates micropores in the range of 0.68-0.73 nm for three-fold SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membrane. SEM characterization of three-fold SiBCN/{gamma}-Al{sub 2}O{sub 3}/{alpha}-Al{sub 2}O{sub 3} membrane shows the thickness of SiBCN membrane layer is 2.8 {mu}m; gas permeance measurements of the membrane shows H{sub 2}/CO selectivity of about 10.5 and the H{sub 2} permeance of about 1.05 x 10{sup -8} mol m{sup -2}s{sup -1}Pa{sup -1}. The observed gas permeation properties point out that the transportation of gas molecules through the membrane is governed by both

A single-ligand ultra-microporous MOF for precombustion CO2 capture and hydrogen purification.

Science.gov (United States)

Nandi, Shyamapada; De Luna, Phil; Daff, Thomas D; Rother, Jens; Liu, Ming; Buchanan, William; Hawari, Ayman I; Woo, Tom K; Vaidhyanathan, Ramanathan

2015-12-01

Metal organic frameworks (MOFs) built from a single small ligand typically have high stability, are rigid, and have syntheses that are often simple and easily scalable. However, they are normally ultra-microporous and do not have large surface areas amenable to gas separation applications. We report an ultra-microporous (3.5 and 4.8 Å pores) Ni-(4-pyridylcarboxylate)2 with a cubic framework that exhibits exceptionally high CO2/H2 selectivities (285 for 20:80 and 230 for 40:60 mixtures at 10 bar, 40°C) and working capacities (3.95 mmol/g), making it suitable for hydrogen purification under typical precombustion CO2 capture conditions (1- to 10-bar pressure swing). It exhibits facile CO2 adsorption-desorption cycling and has CO2 self-diffusivities of ~3 × 10(-9) m(2)/s, which is two orders higher than that of zeolite 13X and comparable to other top-performing MOFs for this application. Simulations reveal a high density of binding sites that allow for favorable CO2-CO2 interactions and large cooperative binding energies. Ultra-micropores generated by a small ligand ensures hydrolytic, hydrostatic stabilities, shelf life, and stability toward humid gas streams.

Development of highly microporous activated carbon from the alcoholic beverage industry organic by-products

International Nuclear Information System (INIS)

Nieto-Delgado, C.; Terrones, M.; Rangel-Mendez, J.R.

2011-01-01

This work has the aim to employ the agave bagasse, a waste from Tequila and Mescal industries, to obtain a product of high commercial value such as activated carbon. The activated carbon production methodology was based on a chemical activation, by using ZnCl 2 and H 3 PO 4 as activating agent and agave bagasse as a natural source of carbon. The activation temperature (150-450 o C), activation time (0-60 min) and weight ratio of activating agent to precursor (0.2-4) were studied. The produced carbon materials were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and nitrogen physisorption at -196 o C. In addition, the activating agent recovery was evaluated. We were able to obtain highly microporous activated carbons with micropore volumes between 0.24 and 1.20 cm 3 /g and a surface area within 300 and 2139 m 2 /g. These results demonstrated the feasibility to treat the industrial wastes of the Tequila and Mescal industries, being this wastes an excellent precursor to produce highly microporous activated carbons that can be processed at low activation temperatures in short times, with the possibility of recycling the activating agent.

Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

Science.gov (United States)

Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

2005-12-15

The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

An Ideal Electrode Material, 3D Surface-Microporous Graphene for Supercapacitors with Ultrahigh Areal Capacitance

International Nuclear Information System (INIS)

Chang, Liang; Stacchiola, Dario J.; Hu, Yun Hang

2017-01-01

The efficient charge accumulation of an ideal supercapacitor electrode requires abundant micropores and its fast electrolyte-ions transport prefers meso/macropores. But, current electrode materials cannot meet both requirements, resulting in poor performance. We creatively constructed three-dimensional cabbage-coral-like graphene as an ideal electrode material, in which meso/macro channels are formed by graphene walls and rich micropores are incorporated in the surface layer of the graphene walls. The unique 3D graphene material can achieve a high gravimetric capacitance of 200 F/g with aqueous electrolyte, 3 times larger than that of commercially used activated carbon (70.8 F/g). Furthermore, it can reach an ultrahigh areal capacitance of 1.28 F/cm"2 and excellent rate capability (83.5% from 0.5 to 10 A/g) as well as high cycling stability (86.2% retention after 5000 cycles). The excellent electric double-layer performance of the 3D graphene electrode can be attributed to the fast electrolyte ion transport in the meso/macro channels and the rapid and reversible charge adsorption with negligible transport distance in the surface micropores.

Facile synthesis of triazine-triphenylamine-based microporous covalent polymer adsorbent for flue gas CO2 capture

KAUST Repository

Das, Swapan Kumar

2017-07-17

The sustainable capture and sequestration of CO2 from flue gas emission is an important and unavoidable challenge to control greenhouse gas release and climate change. In this report, we describe a triazine-triphenylamine-based microporous covalent organic polymer under mild synthetic conditions. 13C and 15N solid-state NMR and FTIR analyses confirm the linkage of the triazine and triphenylamine components in the porous polymer skeleton. The material is composed of spherical particles 1.0 to 2.0 μm in size and possesses a high surface area (1104 m2/g). The material exhibits superb chemical robustness under acidic and basic conditions and high thermal stability. Single-component gas adsorption exhibits an enhanced CO2 uptake of 3.12 mmol/g coupled with high sorption selectivity for CO2/N2 of 64 at 273 K and 1 bar, whereas the binary gas mixture breakthrough study using a model flue gas composition at 298 K shows a high CO2/N2 selectivity of 58. The enhanced performance is attributed to the high Lewis basicity of the framework, as it favors the interaction with CO2.

Multifunction Sr, Co and F co-doped microporous coating on titanium of antibacterial, angiogenic and osteogenic activities

OpenAIRE

Jianhong Zhou; Lingzhou Zhao

2016-01-01

Advanced multifunction titanium (Ti) based bone implant with antibacterial, angiogenic and osteogenic activities is stringently needed in clinic, which may be accomplished via incorporation of proper inorganic bioactive elements. In this work, microporous TiO2/calcium-phosphate coating on Ti doped with strontium, cobalt and fluorine (SCF-TiCP) was developed, which had a hierarchical micro/nano-structure with a microporous structure evenly covered with nano-grains. SCF-TiCP greatly inhibited t...

Photoelectrocatalytic property of microporous Pt-TiO2/Ti electrodes

International Nuclear Information System (INIS)

Hung, Chung-Hsuang; Wu, Kee-Rong; Yeh, Chung-Wei; Sun, Jui-Ching; Hsu, Chuan-Jen

2013-01-01

This study investigates the photoelectrocatalytic (PEC) property of microporous WO 3 -loaded TiO 2 /Ti layer, prepared via micro-arc oxidation (MAO) of Ti plate, followed by sputtering deposition of a thin Pt layer as a Pt-TiO 2 /Ti electrode. The WO 3 -loaded TiO 2 layer which is associated with a more acidic surface forms many local electrochemical cells on its micro-pores immersed in cationic dye solution. The electrocatalytic (EC) reactions can take place in the local cells by the applied electrons. A low resistivity that is accomplished by MAO technique and by platinization offers an easy path for the electron motions in the Pt-TiO 2 /Ti electrode. All these features make the EC oxidation of aqueous dye pollutants practically feasible without using counter electrodes and supporting electrolytes. Our experiments demonstrate that, under PEC condition, the Pt-TiO 2 /Ti shows the highest degradation rate constant of 0.83 h − 1 at an applied bias of 1.0 V and exhibits significantly high PEC and EC oxidation activities at a low applied bias of 0.25 V. This is attributable to high anodic currents generated in the Pt-TiO 2 /Ti even at low bias. The modified microporous electrodes conclusively reveal a very interesting EC property as a two double-sided device that functions the PEC and EC oxidation simultaneously without a need of supporting electrolyte and expensive Pt cathode. - Highlights: ► Pt-TiO 2 /Ti exhibits enhanced photoelectrocatalytic (PEC) activity at low applied bias. ► The proposed device uses low applied bias (< 1.0 V) with no explicit cathode. ► PEC oxidation can be performed without supporting electrolyte and Pt cathode

Micropore sintering in UO2 irradiated below 11000C in the Winfrith SGHWR

International Nuclear Information System (INIS)

Banks, D.A.; Clough, D.J.

1979-01-01

The densification behaviour of UO 2 irradiated in the Winfrith steam generating heavy water reactor has been examined using optical and scanning electron microscope techniques and by measuring the densities of whole pellets and small cores removed from pellet sections. Micrography has shown that in the temperature range 400 to 1000 0 C densification is due to the in-factor sintering of micropores (approximately< 2 m in diameter) with a temperature dependency defined by an activation energy of 21.7 kJ/mol. Pore area measurements, allied to previously published work, have led to the derivation of an equation which can be used to predict micropore volume changes occurring during irradiation and takes account of both the temperature and burn-up dependency of pore sintering. (author)

Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

International Nuclear Information System (INIS)

Feng, Xiaojuan; Shi, Yanlong; Jin, Shuping

2015-01-01

The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g"−"1 at 0.3 A g"−"1 current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g"−"1), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

Energy Technology Data Exchange (ETDEWEB)

Feng, Xiaojuan, E-mail: cherry-820@163.com; Shi, Yanlong; Jin, Shuping

2015-10-30

The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g{sup −1} at 0.3 A g{sup −1} current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g{sup −1}), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

Structural study and fluorescent property of a novel organic microporous crystalline material

International Nuclear Information System (INIS)

Cheng, Zhao; Yang, Bingqin; Yang, Meipan; Zhang, Binglin

2014-01-01

A novel microporous organic material [(2-{2-[2-(bis-methoxycarbonylmethylamino)phenoxy] ethoxy}-4-benzimidazole-phenyl)methoxycarbonylmethylamino]acetic acid methyl ester 6 was synthesized and characterized by single crystal X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), electron spray ionization-mass spectrometry (ESI-HRMS), X-ray powder diffraction (PXRD), 1 H and 13 C NMR. 6 crystallizes in the centrosymmetric monoclinic space group C2/c, with unit cell parameters a = 35.648(3) Å, b = 14.3240(12) Å, c = 15.3693(13) Å, α = 90.00, β = 94.8190(10), γ = 90.00, V = 7820.16 Å 3 and Z = 8 at 296(2) K. As indicated by crystal packing, the molecular conjugation planes arrange along the c axis to form micropores due to the hydrogen bonds. In addition, the fluorescent spectrum and luminescence lifetime were studied for 6. (author)

Ambient-temperature fabrication of microporous carbon terminated with graphene walls by sputtering process for hydrogen storage applications

International Nuclear Information System (INIS)

Banerjee, Arghya Narayan; Joo, Sang Woo; Min, Bong-Ki

2013-01-01

A very thin amorphous carbon film (10–30 nm), has been bombarded with sputtered Cr nanoparticles, resulting in inelastic collision between the nanoparticles and the nuclei of the C-atoms causing atom displacement and re-arrangement into graphene layers. The process occurs at ambient temperature. Fabrication of graphitic microporous carbon terminated with few-to-multilayer graphene walls has been verified by Raman spectroscopy and scanning transmission electron microscopy. High resolution transmission electron micrographs reveal that the formation of graphene layers is highly sensitive to the sputtering parameters. With a gradual increase in the sputtering voltage/current density/time from 3.5 kV/40 mA–cm −2 /1.0 min to 5.0 kV/70 mA–cm −2 /3.0 min the graphitic domains are found to transform from semi-graphitized layers to well-defined, highly ordered, larger-area graphene walls within the microporous network. The mechanism of this graphitic microporous carbon formation is assumed to be due to two simultaneous processes: in one hand, the sputtering plasma, containing energetic ions and sub-atomic particles, act as dry-etchant to activate the a:C film to transform it into microporous carbon, whereas on the other hand, the charged metal nanoparticle/ion bombardment under sputtering resulted in the inelastic collision between the nanoparticles/ions and the nuclei of the C atoms followed by atom displacement (and displacement cascade) and re-arrangement into ordered structure to form graphitic domains within the microporous carbon network. H 2 storage experiment of the samples depicts excellent hydrogen storage properties. This simple, cost-effective, complementary-metal-oxide-semiconductor-compatible, single-step process of metal-graphene hybrid nanomaterial formation may find interesting applications in the field of optoelectronics and biotechnology. Additionally, this method can be adopted easily for the incorporation of transition metals into graphene and

Micropore extrusion-induced alignment transition from perpendicular to parallel of cylindrical domains in block copolymers.

Science.gov (United States)

Qu, Ting; Zhao, Yongbin; Li, Zongbo; Wang, Pingping; Cao, Shubo; Xu, Yawei; Li, Yayuan; Chen, Aihua

2016-02-14

The orientation transition from perpendicular to parallel alignment of PEO cylindrical domains of PEO-b-PMA(Az) films has been demonstrated by extruding the block copolymer (BCP) solutions through a micropore of a plastic gastight syringe. The parallelized orientation of PEO domains induced by this micropore extrusion can be recovered to perpendicular alignment via ultrasonication of the extruded BCP solutions and subsequent annealing. A plausible mechanism is proposed in this study. The BCP films can be used as templates to prepare nanowire arrays with controlled layers, which has enormous potential application in the field of integrated circuits.

Large-aperture focusing of x rays with micropore optics using dry etching of silicon wafers.

Science.gov (United States)

Ezoe, Yuichiro; Moriyama, Teppei; Ogawa, Tomohiro; Kakiuchi, Takuya; Mitsuishi, Ikuyuki; Mitsuda, Kazuhisa; Aoki, Tatsuhiko; Morishita, Kohei; Nakajima, Kazuo

2012-03-01

Large-aperture focusing of Al K(α) 1.49 keV x-ray photons using micropore optics made from a dry-etched 4 in. (100 mm) silicon wafer is demonstrated. Sidewalls of the micropores are smoothed with high-temperature annealing to work as x-ray mirrors. The wafer is bent to a spherical shape to collect parallel x rays into a focus. Our result supports that this new type of optics allows for the manufacturing of ultralight-weight and high-performance x-ray imaging optics with large apertures at low cost. © 2012 Optical Society of America

Granular bamboo-derived activated carbon for high CO(2) adsorption: the dominant role of narrow micropores.

Science.gov (United States)

Wei, Haoran; Deng, Shubo; Hu, Bingyin; Chen, Zhenhe; Wang, Bin; Huang, Jun; Yu, Gang

2012-12-01

Cost-effective biomass-derived activated carbons with a high CO(2) adsorption capacity are attractive for carbon capture. Bamboo was found to be a suitable precursor for activated carbon preparation through KOH activation. The bamboo size in the range of 10-200 mesh had little effect on CO(2) adsorption, whereas the KOH/C mass ratio and activation temperature had a significant impact on CO(2) adsorption. The bamboo-derived activated carbon had a high adsorption capacity and excellent selectivity for CO(2) , and also the adsorption process was highly reversible. The adsorbed amount of CO(2) on the granular activated carbon was up to 7.0 mmol g(-1) at 273 K and 1 bar, which was higher than almost all carbon materials. The pore characteristics of activated carbons responsible for high CO(2) adsorption were fully investigated. Based on the analysis of narrow micropore size distribution of several activated carbons prepared under different conditions, a more accurate micropore range contributing to CO(2) adsorption was proposed. The volume of micropores in the range of 0.33-0.82 nm had a good linear relationship with CO(2) adsorption at 273 K and 1 bar, and the narrow micropores of about 0.55 nm produced the major contribution, which could be used to evaluate CO(2) adsorption on activated carbons. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of mesohollow and microporous carbon nanofiber and its application in cathode material for lithium–sulfur batteries

International Nuclear Information System (INIS)

Wu, Yuanhe; Gao, Mingxia; Li, Xiang; Liu, Yongfeng; Pan, Hongge

2014-01-01

Highlights: • Mesohollow and microporous carbon fibers were prepared via electrospinning and carbonization. • Sulfur (S) incorporated into the porous fibers by thermal heating in 60 wt.%, forming composite. • S fills fully in the micropores and partially in the mesohollows of the carbon fibers. • The composite shows high capacity and capacity retention as cathode material for Li–S batteries. • Mesohollow and microporous structure is effective in improving the property of S cathode. - Abstract: Mesohollow and microporous carbon nanofibers (MhMpCFs) were prepared by a coaxial electrospinning with polyacrylonitrile (PAN) and polymethylmethacrylate (PMMA) as outer and inner spinning solutions followed by a carbonization. The carbon fibers were thermal treated with sublimed sulfur to form S/MhMpCFs composite, which was used as cathode material for lithium–sulfur batteries. Electrochemical study shows that the S/MhMpCFs cathode material provides a maximum capacity of 815 mA h/g after several cycles of activation, and the capacity retains 715 mA h/g after 70 cycles, corresponding to a retention of 88%. The electrochemical property of the S/MhMpCFs composite is much superior than the S-incorporated solid carbon fibers prepared from electrospinning of single PAN. The mechanism of the enhanced electrochemical property of the S/MhMpCFs composite is discussed

Combined Effect of a Microporous Layer and Type I Collagen Coating on a Biphasic Calcium Phosphate Scaffold for Bone Tissue Engineering

Directory of Open Access Journals (Sweden)

Mun-Hwan Lee

2015-03-01

Full Text Available In this study, type I collagen was coated onto unmodified and modified microporous biphasic calcium phosphate (BCP scaffolds. Surface characterization using a scanning electron microscope (SEM and a surface goniometer confirmed the modification of the BCP coating. The quantity of the collagen coating was investigated using Sirius Red staining, and quantitative assessment of the collagen coating showed no significant differences between the two groups. MG63 cells were used to evaluate cell proliferation and ALP activity on the modified BCP scaffolds. The modified microporous surfaces showed low contact angles and large surface areas, which enhanced cell spreading and proliferation. Coating of the BCP scaffolds with type I collagen led to enhanced cell-material interactions and improved MG63 functions, such as spreading, proliferation, and differentiation. The micropore/collagen-coated scaffold showed the highest rate of cell response. These results indicate that a combination of micropores and collagen enhances cellular function on bioengineered bone allograft tissue.

Selective oxidation of benzene and cyclohexane using amorphous microporous mixed oxides; Selektive Oxidation von Benzol und Cyclohexan mit amorphen mikroporoesen Mischoxiden

Energy Technology Data Exchange (ETDEWEB)

Stoeckmann, M.

2000-07-01

Phenol was to be produced by direct oxidation of benzene with environment-friendly oxidants like hydrogen peroxide, oxygen, or ozone. Catalysts were amorphous microporous mixed oxides whose properties can be selected directly in the sol-gel synthesis process. Apart from benzene, also cyclohexane was oxidized with ozone using AMM catalysts in order to get more information on the potential of ozone as oxidant in heterogeneously catalyzed reactions. [German] Ziel dieser Arbeit war die Herstellung von Phenol durch die Direktoxidation von Benzol mit umweltfreundlichen Oxidationsmitteln wie Wasserstoffperoxid, Sauerstoff oder Ozon. Als Katalysatoren dienten amorphe mikroporoese Mischoxide, da deren Eigenschaften direkt in der Synthese durch den Sol-Gel-Prozess gezielt eingestellt werden koennen. Neben Benzol wurde auch Cyclohexan mit Ozon unter der Verwendung von AMM-Katalysatoren oxidiert, um das Potential von Ozon als Oxiationsmittel in heterogen katalysierten Reaktionen naeher zu untersuchen. (orig.)

Electron transfer reactions in microporous solids. Progress report, September 1990--January 1993

Energy Technology Data Exchange (ETDEWEB)

Mallouk, T.E.

1993-01-01

Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H{sub 2} and I{sub 3}{sup {minus}}, or H{sub 2} and O{sub 2)} from each other. Spectroscopic and electrochemical methods are used to study the kinetics of electron transfer reactions in these hybrid molecular/solid state assemblies.

Structural study and fluorescent property of a novel organic microporous crystalline material

Energy Technology Data Exchange (ETDEWEB)

Cheng, Zhao; Yang, Bingqin; Yang, Meipan; Zhang, Binglin, E-mail: yangbq@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University (China)

2014-01-15

A novel microporous organic material [(2-{2-[2-(bis-methoxycarbonylmethylamino)phenoxy] ethoxy}-4-benzimidazole-phenyl)methoxycarbonylmethylamino]acetic acid methyl ester 6 was synthesized and characterized by single crystal X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), electron spray ionization-mass spectrometry (ESI-HRMS), X-ray powder diffraction (PXRD), {sup 1}H and {sup 13}C NMR. 6 crystallizes in the centrosymmetric monoclinic space group C2/c, with unit cell parameters a = 35.648(3) Å, b = 14.3240(12) Å, c = 15.3693(13) Å, a = 90.00, ß = 94.8190(10), γ = 90.00, V = 7820.16 Å{sup 3} and Z = 8 at 296(2) K. As indicated by crystal packing, the molecular conjugation planes arrange along the c axis to form micropores due to the hydrogen bonds. In addition, the fluorescent spectrum and luminescence lifetime were studied for 6. (author)

Study of microporous PVA/PVC composite polymer membrane and it application to MnO2 capacitors

International Nuclear Information System (INIS)

Yang, C.-C.; Wu, G.M.

2009-01-01

A microporous poly(vinyl alcohol)/poly(vinyl chloride) (PVA/PVC) composite polymer membrane was successfully synthesized by a solution casting method and a preferential dissolution method. The characteristic properties of PVA/PVC composite polymer membranes were systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), micro-Raman spectroscopy and AC impedance spectroscopy. The PVA/PVC composite polymer membrane shows excellent thermal property, dimensional stability, and the ionic conductivity; it is due to the addition of secondary PVC polymer fillers. The MnO 2 capacitors with the PVA/PVC composite polymer membrane with 1 M Na 2 SO 4 was assembled and examined. It was found that the MnO 2 capacitor based on a microporous PVA/5 wt.%PVC composite polymer electrolyte membrane exhibited the maximum specific capacitance of 238 F g -1 and the current efficiency of 99% at 25 mV s -1 after 1000 cycle test. The result demonstrates that the novel microporous PVA/PVC composite polymer membrane is a potential candidate for use on the capacitors

Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al nanoparticles as a high microwave absorption material

Energy Technology Data Exchange (ETDEWEB)

Pang, Yu; Xie, Xiubo; Li, Da [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China); Chou, Wusheng [School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Liu, Tong, E-mail: tongliu@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China)

2017-03-15

The Al{sub 3}Ni{sub 2}@Al nanoparticles (NPs) were prepared from Ni{sub 45}Al{sub 55} master alloy by hydrogen plasma-metal reaction method, and were subsequently dealloyed to produce porous Ni@NiO NPs of 36 nm. The pore size ranges from 0.7 to 1.6 nm, leading to large specific surface area of 69.5 m{sup 2}/g and big pore volume of 0.507 cc/g. The saturation magnetization (M{sub S}) and coercivity (H{sub C}) of the microporous Ni@NiO NPs are 11.5 emu/g and 5.2 Oe. They exhibit high microwave absorption performance with a minimum reflection coefficient (RC) of −86.9 dB and an absorption bandwidth of 2.6 GHz (RC≤−10 dB) at thickness of 4.5 mm. The enhanced microwave absorption properties are attributed to the synergistic effect of the magnetic Ni core and dielectric NiO shell, and the micropore architecture. The NPs with micropore morphology and core/shell structure open a new way to modify the microwave absorption performance. - Graphical abstract: The microporous Ni/NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al NPs exhibit high microwave absorption intensity (−86.9 dB) and wide absorption bandwidth (2.6 GHz for RC≤−10 dB). - Highlights: • Microporous Ni/NiO nanoparticals were prepared by chemically dealloying method. • They possessed micropores of 0.7–1.6 nm with a surface area of 69.5 m{sup 2}/g. • They showed high microwave absorption intensity and wide absorption bandwidth. • Microwave absorption mechanism was explained by micropore and core/shell structures.

A Li+-conductive microporous carbon–sulfur composite for Li-S batteries

International Nuclear Information System (INIS)

Zhang, Wenhua; Qiao, Dan; Pan, Jiaxin; Cao, Yuliang; Yang, Hanxi; Ai, Xinping

2013-01-01

Highlights: ► A carbon–sulfur composite was prepared by vaporizing sulfur into the nanopores of Li + -conductive carbon microspheres. ► The redox reaction of S 8 molecules embedded in the nanopores of carbon microspheres proceeds through a solid–solid mechanism at the S/C interfaces. ► The carbon–sulfur composite exhibits a stable cycling performance and a superior high coulombic efficiency of 100%. - Abstract: In this paper, we propose a new strategy to develop high performance sulfur electrode by impregnating sulfur into the micropores of a Li + -insertable carbon matrix with the simultaneous use of a carbonate electrolyte, which does not dissolve polysulfides, to restrain the solution of the reaction intermediates of sulfur. To proof this concept, we prepared a Li + -insertable microporous carbon–sulfur composite by vaporizing sulfur into the micropores of the nanofiber-wired carbon microspheres. The experimental results demonstrate that, in the carbonate electrolyte of 1 M LiPF 6 /PC-EC-DEC, such S/C composite electrode exhibits not only stable cycling performance with a reversible capacity of 720 mAh g −1 after 100 cycles, but also superior high coulombic efficiency of ∼100% upon extended cycling (except the first three cycles). The structural and electrochemical analysis indicates that the improved electrochemical behaviors of the S/C composite arise from a new reaction mechanism, in which Li + ions and electrons transport through the carbon matrix into the interior of the cathode and then react with the embedded sulfur in the S/C solid–solid interfaces, avoiding the solution of the intermediates into the bulk electrolyte. More significantly, the structural design and working mechanism of such a sulfur cathode could be extended to a variety of poorly conductive and easily soluble redox-active materials for battery applications.

Respiration activity of Escherichia coli entrapped in a cone-shaped microwell and cylindrical micropore monitored by scanning electrochemical microscopy (SECM).

Science.gov (United States)

Kaya, Takatoshi; Numai, Daisuke; Nagamine, Kuniaki; Aoyagi, Shigeo; Shiku, Hitoshi; Matsue, Tomokazu

2004-06-01

The metabolic activity of E. coli cells embedded in collagen gel microstructures in a cone-shaped well and in a cylindrical micropore was investigated using scanning electrochemical microscopy (SECM), based on the oxygen consumption rate and the conversion rate from ferrocyanide to ferricyanide. The analysis of the concentration profiles for oxygen and ferrocyanide afforded the oxygen consumption rate and the ferrocyanide production rate. A comparison indicated that the ferrocyanide production rates were larger than the oxygen consumption rate, and also that the rates observed in the cylindrical micropore were larger than those observed in the cone-shaped well. The ferrocyanide production rate of a single E. coli cell was calculated to be (5.4 +/- 2.6) x 10(-19) mol s(-1), using a cylindrical micropore system.

Transition-Metal-Catalyzed Chain-Growth Polymerization of 1,4-Diethynylbenzene into Microporous Crosslinked Poly(phenylacetylene)s: the Effect of Reaction Conditions

Czech Academy of Sciences Publication Activity Database

Slováková, E.; Zukal, Arnošt; Brus, Jiří; Balcar, Hynek; Brabec, Libor; Bondarev, D.; Sedláček, J.

2014-01-01

Roč. 215, č. 19 (2014), s. 1855-1869 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GAP108/11/1661 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : Conjugated microporous polymers * Conjugated polymers * Microporous organic polymers Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 2.616, year: 2014

Synthesis and Characterization of a Novel Microporous Dihydroxyl-Functionalized Triptycene-Diamine-Based Polyimide for Natural Gas Membrane Separation

KAUST Repository

Alaslai, Nasser Y.

2017-07-10

An intrinsically microporous polyimide is synthesized in m-cresol by a one-pot high-temperature condensation reaction of 4,4\\'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and newly designed 2,6 (7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH). The 6FDA-DAT1-OH polyimide is thermally stable up to 440 °C, shows excellent solubility in polar solvents, and has moderately high Brunauer-Teller-Emmett (BET) surface area of 160 m2 g-1 , as determined by nitrogen adsorption at -196 °C. Hydroxyl functionalization applied to the rigid 3D triptycene-based diamine building block results in a polyimide that exhibits moderate pure-gas CO2 permeability of 70 Barrer combined with high CO2 /CH4 selectivity of 50. Mixed-gas permeation studies demonstrate excellent plasticization resistance of 6FDA-DAT1-OH with impressive performance as potential membrane material for natural gas sweetening with a CO2 permeability of 50 Barrer and CO2 /CH4 selectivity of 40 at a typical natural gas well partial pressure of 10 atm.

Analysis and theory of gas transport in microporous sol-gel derived ceramic membranes

NARCIS (Netherlands)

de Lange, R.S.A.; de Lange, Rob; Keizer, Klaas; Burggraaf, Anthonie; Burggraaf, A.J.

1995-01-01

Sol-gel modification of mesoporous alumina membranes is a very successful technique to improve gas separation performance. Due to the formed microporous top layer, the membranes show activated transport and molecular sieve-like separation factors. This paper concentrates on the mechanism of

Ordered microporous layered lanthanide 1,3,5-benzenetriphosphonates pillared with cationic organic molecules.

Science.gov (United States)

Araki, Takahiro; Kondo, Atsushi; Maeda, Kazuyuki

2015-04-13

Novel isomorphous pillared-layer-type crystalline lanthanide 1,3,5-benzenetriphosphonates were prepared with bpy and dbo as organic pillars (LnBP-bpy and LnBP-dbo; Ln: Ce, Pr, and Nd). Ab initio crystal structure solution using synchrotron X-ray powder diffraction data revealed that the organic pillars do not exist as neutral coordinating ligands but as cationic molecules. Especially the LnBP-dbo phases have ordered interlayer space filled with water molecules between the dbo pillars, and the interlayer water is successfully removed by heating under vacuum with slightly distorted but basically retained pillared layer structures. Microporosity of the materials is confirmed by adsorption of nitrogen, carbon dioxide, and hydrogen gases. Such microporous layered metal phosphonates pillared with cationic molecules should be unprecedented and should offer new strategies to design ordered microporous materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory and computer simulation of structure, transport, and flow of fluid in micropores

International Nuclear Information System (INIS)

Davis, H.T.; Bitsanis, I.; Vanderlick, T.K.; Tirrell, M.V.

1987-01-01

An overview is given of recent progress made in our laboratory on this topic. The density profiles of fluid in micropores are found by solving numerically an approximate Yvon-Born-Green equation. A related local average density model (LADM) allows prediction of transport and flow in inhomogeneous fluids from density profiles. A rigorous extension of the Enskog theory of transport is also outlined. Simple results of this general approach for the tracer diffusion and Couette flow between planar micropore walls are presented. Equilibrium and flow (molecular dynamics) simulations are compared with the theoretical predictions. Simulated density profiles of the micropore fluid exhibit substantial fluid layering. The number and sharpness of fluid layers depend sensitively on the pore width. The solvation force and the pore average density and diffusivity are oscillating functions of the pore width. The theoretical predictions for these quantities agree qualitatively with the simulation results. The flow simulations indicate that the flow does not affect the fluid structure and diffusivity even at extremely high shear rates (10/sup 10/s/sup -1/). The fluid structure induces large deviations of the shear stress and the effective viscosity from the bulk fluid values. The flow velocity profiles are correlated with the density profiles and differ from those of a bulk fluid. The LADM and extended Enskog theory predictions for the velocity profiles and the pore average diffusivity agree very well with each other and with the simulation results. The LADM predictions for the shear stress and the effective viscosity agrees fairly well with the simulation results

Effects of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on the adsorption of p-nitroaniline in aqueous solution

International Nuclear Information System (INIS)

Xiao, Guqing; Wen, Ruimin; Wei, Dongmei; Wu, Dan

2014-01-01

Graphical abstract: The hyper-cross-linked polymeric adsorbents (GQ-05 and GQ-03) with different steric hindrance of micropores were designed. The adsorption capacity and adsorption rate of PNA onto the two adsorbents followed the order GQ-05 > GQ-03. The steric hindrance of micropores was a crucial factor for the adsorption capacity and adsorption rate order. - Highlights: • Two adsorbents with different steric hindrance of micropores were designed. • The adsorption capacity and adsorption rate followed the order GQ-05 > GQ-03. • The steric hindrance of micropores was a crucial factor for the order. - Abstract: A hyper-cross-linked polymeric adsorbent with “-CH 2 -phenol-CH 2 -” as the cross-linked bridge (denoted GQ-05), and another hyper-cross-linked polymeric adsorbent with “-CH 2 -p-cresol-CH 2 -” as the cross-linked bridge (denoted GQ-03) were synthesized to reveal the effect of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on adsorption capacity and adsorption rate of p-nitroaniline (PNA) from aqueous solution. The results of adsorption kinetics indicated the order of the adsorption rate GQ-05 > GQ-03. The pseudo-first-order rate equation could describe the entire adsorption process of PNA onto GQ-05 while the equation characterized the adsorption process of GQ-03 in two stages. The order of the adsorption capacity GQ-05 > GQ-03 was demonstrated by thermodynamic analysis and dynamic adsorption. The steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent was a crucial factor for the order of the adsorption capacity and adsorption rate

Synthesis and characterization of a microporous 6FDA-polyimide made from a novel carbocyclic pseudo Tröger's base diamine: Effect of bicyclic bridge on gas transport properties

KAUST Repository

Abdulhamid, Mahmoud A.

2017-10-12

A newly designed carbocyclic pseudo Tröger\\'s base diamine (CTB) monomer, 2,8-dimethyl-3,9-diamino-5,6,11,12-tetrahydro-5,11-methanodibenzo[a,e][8]annulene (CTBDA) and its isomeric analogue 2,8-dimethyl-(1,7)(4,10)(3,9)-diamino-5,6,11,12-tetrahydro-5,11-methanodibenzo[a,e][8]annulene (iCTBDA), were designed for the synthesis of microporous 6FDA-based polyimides (6FDA-CTBDA and 6FDA-iCTBDA). Both polyimides were soluble, exhibited excellent thermal stability of ∼490 °C, and had high surface areas of 587 m2 g−1 (6FDA-CTBDA) and 562 m2 g−1 (6FDA-iCTBDA). A 6FDA-based polyimide derived from 4,10-dimethyl-3,9-diamino-6H,12H-5,11-methanodibenzo[b,f][1,5]-diazocine (6FDA-TBDA) was made for comparison to investigate the effects of the basic tertiary nitrogen functionality in the Tröger\\'s base diamine on the polymer properties relative to the carbocyclic 6FDA-CTBDA analogue. 6FDA-TBDA displayed lower gas permeabilities but moderately higher gas-pair permselectivities than 6FDA-CTBDA. The enhanced permselectivity of 6FDA-TBDA resulted exclusively from higher diffusion-based selectivity. Direct gas sorption measurements demonstrated that the basicity in the Tröger\\'s base bridge moiety enhanced the sorption capacity of CO2 only slightly and had no effect on the CO2/CH4 solubility selectivity in 6FDA-TBDA vs. 6FDA-CTBDA.

An ultrasonic analysis of the comparative efficiency of various cardiotomy reservoirs and micropore blood filters.

Science.gov (United States)

Pearson, D T; Watson, B G; Waterhouse, P S

1978-01-01

The ability of 12 commercially available cardiotomy reservoirs to remove bubbles from aspirated blood was investigated by means of a simulated cardiopulmonary bypass circuit and an ultrasonic microbubble detector. Performance varied considerably. The number of gaseous microemboli remaining after passage of blood through the reservoir was reduced by (a) holding the blood in the reservoir, (b) reducing the volume of air mixed with the aspirated blood, and (c) using a reservoir that did not induce turbulence and that contained integral micropore filtration material. Further micropore filtration of the blood after passage through the cardiotomy reservoir was beneficial, and significantly more bubbles were extracted when the microfilter was sited below the reservoir than when it was placed in the arterial line. PMID:684672

Subnanopore filling during water vapor adsorption on microporous silica thin films as seen by low-energy positron annihilation

Science.gov (United States)

Ito, Kenji; Yoshimoto, Shigeru; O'Rourke, Brian E.; Oshima, Nagayasu; Kumagai, Kazuhiro

2018-02-01

Positron annihilation lifetime spectroscopy (PALS) using a low-energy positron microbeam extracted into air was applied to elucidating molecular-level pore structures formed in silicon-oxide-backboned microporous thin films under controlled humidity conditions; as a result, a direct observation of the interstitial spaces in the micropores filled with water molecules was achieved. It was demonstrated that PALS using a microbeam extracted into air in combination with water vapor adsorption is a powerful tool for the in-situ elucidation of both open and closed subnanoscaled pores of functional thin materials under practical conditions.

Using Microporous Polytetrafluoroethylene Thin Sheets as a Flexible Solar Diffuser to Minimize Sunlight Glint to Cameras in Space

Science.gov (United States)

Choi, Michael K.

2016-01-01

An innovative design of using microporous PTFE thin sheets as a solar diffuser for MLI blankets or mechanical structure has been developed. It minimizes sunlight or stray-light glint to cameras when it is incident on these components in space. A microporous black PTFE thin sheet solar diffuser has been qualified for flight at NASA GSFC and installed to the TAGSAM arm MLI, OCAMS PolyCam sunshade MLI and SamCam motor riser MLI in the NASA OSIRIS-REx mission to meet the SamCam camera BRDF requirement.

Using microporous polytetrafluoroethylene thin sheets as a flexible solar diffuser to minimize sunlight glint to cameras in space

Science.gov (United States)

Choi, Michael K.

2016-09-01

An innovative design of using microporous PTFE thin sheets as a solar diffuser for MLI blankets or mechanical structure has been developed. It minimizes sunlight or stray-light glint to cameras when it is incident on these components in space. A microporous black PTFE thin sheet solar diffuser has been qualified for flight at NASA GSFC and installed to the TAGSAM arm MLI, OCAMS PolyCam sunshade MLI and SamCam motor riser MLI in the NASA OSIRIS-REx mission to meet the SamCam camera BRDF requirement.

An efficient one-step condensation and activation strategy to synthesize porous carbons with optimal micropore sizes for highly selective CO₂ adsorption.

Science.gov (United States)

Wang, Jiacheng; Liu, Qian

2014-04-21

A series of microporous carbons (MPCs) were successfully prepared by an efficient one-step condensation and activation strategy using commercially available dialdehyde and diamine as carbon sources. The resulting MPCs have large surface areas (up to 1881 m(2) g(-1)), micropore volumes (up to 0.78 cm(3) g(-1)), and narrow micropore size distributions (0.7-1.1 nm). The CO₂ uptakes of the MPCs prepared at high temperatures (700-750 °C) are higher than those prepared under mild conditions (600-650 °C), because the former samples possess optimal micropore sizes (0.7-0.8 nm) that are highly suitable for CO₂ capture due to enhanced adsorbate-adsorbent interactions. At 1 bar, MPC-750 prepared at 750 °C demonstrates the best CO₂ capture performance and can efficiently adsorb CO₂ molecules at 2.86 mmol g(-1) and 4.92 mmol g(-1) at 25 and 0 °C, respectively. In particular, the MPCs with optimal micropore sizes (0.7-0.8 nm) have extremely high CO₂/N₂ adsorption ratios (47 and 52 at 25 and 0 °C, respectively) at 1 bar, and initial CO₂/N₂ adsorption selectivities of up to 81 and 119 at 25 °C and 0 °C, respectively, which are far superior to previously reported values for various porous solids. These excellent results, combined with good adsorption capacities and efficient regeneration/recyclability, make these carbons amongst the most promising sorbents reported so far for selective CO₂ adsorption in practical applications.

129Xe nuclear magnetic resonance study of pitch-based activated carbon modified by air oxidation/pyrolysis cycles: a new approach to probe the micropore size.

Science.gov (United States)

Romanenko, Konstantin V; Py, Xavier; d'Espinose de Lacaillerie, Jean-Baptiste; Lapina, Olga B; Fraissard, Jacques

2006-02-23

(129)Xe NMR has been used to study a series of homologous activated carbons obtained from a KOH-activated pitch-based carbon molecular sieve modified by air oxidation/pyrolysis cycles. A clear correlation between the pore size of microporous carbons and the (129)Xe NMR of adsorbed xenon is proposed for the first time. The virial coefficient delta(Xe)(-)(Xe) arising from binary xenon collisions varied linearly with the micropore size and appeared to be a better probe of the microporosity than the chemical shift extrapolated to zero pressure. This correlation was explained by the fact that the xenon collision frequency increases with increasing micropore size. The chemical shift has been shown to vary very little with temperature (less than 9 ppm) for xenon trapped inside narrow and wide micropores. This is indicative of a smooth xenon-surface interaction potential.

A new method for calculating gas content of coal reservoirs with consideration of a micro-pore overpressure environment

Directory of Open Access Journals (Sweden)

Jinxing Song

2017-05-01

Full Text Available When the gas content of a coal reservoir is calculated, the reservoir pressure measured by well logging and well testing is generally used for inversion calculation instead of gas pressure. However, the calculation result is not accurate because the reservoir pressure is not equal to the gas pressure in overpressure environments. In this paper, coal samples of different ranks in Shanxi and Henan are collected for testing the capillary pressure of coal pores. Based on the formation process of CBM reservoirs and the hydrocarbon generation and expulsion history of coal beds, the forming mechanisms of micro-pore overpressure environments in coal reservoirs were analyzed. Accordingly, a new method for calculating the gas content of coal reservoirs with consideration of a micro-pore overpressure environment was developed. And it was used to calculate the gas content of No. 1 coal bed of the 2nd member of Lower Permian Shanxi Fm in the Zhongmacun Coal Mine in Jiaozuo, Henan. It is indicated that during the formation and evolution of coals, some solid organic matters were converted into gas and water, and gas–water contact is surely formed in pores. In the end, capillary pressure is generated, so the gas pressure in micro-pores is much higher than the hydrostatic column pressure, which results in a micro-pore overpressure environment. Under such an environment, gas pressure is higher than reservoir pressure, so the gas content of coal reservoirs calculated previously based on the conventional reservoir pressure evaluation are usually underestimated. It is also found that the micro-pore overpressure environment exerts a dominating effect on the CBM content calculation of 3–100 nm pores, especially that of 3–10 nm pores, but a little effect on that of pores >100 nm. In conclusion, this new method clarifies the pressure environment of CBM gas reservoirs, thereby ensuring the calculation accuracy of gas content of coal reservoirs.

Synthesis of mesoporous SAPO-34 molecular sieves and their applications in dehydration of butanols and ethanol.

Science.gov (United States)

Jun, Jong Won; Jeon, Jaewoo; Kim, Chul-Ung; Jeong, Kwang-Eun; Jeong, Soon-Yong; Jhung, Sung Hwa

2013-04-01

Microporous SAPO-34 molecular sieves were hydrothermally synthesized with microwave irradiation in the presence of tetraethylammonium hydroxide (TEAOH) as a template. SAPO-34 molecular sieves with mesoporosity were also prepared in the presence of carbon black as a hard template. By increasing the content of the carbon black template in the synthesis, the mesopore volume increased. Dehydration of alcohols (butanols and ethanol) was carried out with the synthesized SAPO-34 molecular sieves, and the lifetime of the catalysts for the dehydration reaction increased as the mesoporosity increased. Moreover, the performance of the microporous catalyst synthesized with microwave was better than that of the catalyst obtained with conventional electric heating. The relative performance of the catalytic dehydration may be explained by the mesoporosity and the crystal size. Therefore, it may be concluded that small-sized SAPO-34 molecular sieves with high mesoporosity can be produced efficiently with microwave irradiation in the presence of carbon black template, and the molecular sieves are effective in the stable dehydration of alcohols.

Micropore engineering of carbonized porous aromatic framework (PAF-1) for supercapacitors application.

Science.gov (United States)

Li, Yanqiang; Roy, Soumyajit; Ben, Teng; Xu, Shixian; Qiu, Shilun

2014-07-07

Micropore engineering of porous carbons on the effect of capacitance was explored using a carbonized porous aromatic framework (PAF-1). The porous carbons obtained through different carbonization methods show different pore structures enabling us to do this. The capacitance was measured both in aqueous electrolyte and different organic electrolytes. The porous carbons prepared by KOH activation show both high microporous volume, which is beneficial for charge storage, and mesoporous volume, which is devoted to fast ion diffusion in the pores; properties which are highly desirable. It shows a capacitance as high as 280 F g(-1) and 203 F g(-1) at a current density of 1 A g(-1) in 6.0 M KOH and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI), respectively. We also demonstrate the effect of diffusion and that of geometric packing of the electrolyte ions in the pores, where a commensurate match of the electrolyte ions with the pores of carbonized materials control and influence significantly the capacitance of these materials.

Injectable and microporous scaffold of densely-packed, growth factor-encapsulating chitosan microgels.

Science.gov (United States)

Riederer, Michael S; Requist, Brennan D; Payne, Karin A; Way, J Douglas; Krebs, Melissa D

2016-11-05

In this work, an emulsion crosslinking method was developed to produce chitosan-genipin microgels which acted as an injectable and microporous scaffold. Chitosan was characterized with respect to pH by light scattering and aqueous titration. Microgels were characterized with swelling, light scattering, and rheometry of densely-packed microgel solutions. The results suggest that as chitosan becomes increasingly deprotonated above the pKa, repulsive forces diminish and intermolecular attractions cause pH-responsive chain aggregation; leading to microgel-microgel aggregation as well. The microgels with the most chitosan and least cross-linker showed the highest yield stress and a storage modulus of 16kPa when condensed as a microgel paste at pH 7.4. Two oppositely-charged growth factors could be encapsulated into the microgels and endothelial cells were able to proliferate into the 3D microgel scaffold. This work motivates further research on the applications of the chitosan microgel scaffold as an injectable and microporous scaffold in regenerative medicine. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and Characterization of Non-Conventional Micro-Porous Layers for PEM Fuel Cells

Directory of Open Access Journals (Sweden)

Riccardo Balzarotti

2015-07-01

Full Text Available Gas diffusion medium (GDM is a crucial component in proton exchange membrane fuel cells (PEMFCs. Being composed of a gas diffusion layer (GDL with a micro-porous layer (MPL coated onto it, it ensures a proper water management due to the highly hydrophobic materials employed in cell assembly. In current commercial applications, the desired water repellent behaviour is usually obtained by using polytetrafluoroethylene (PTFE. In this work, Fluorolink® P56 (Solvay Specialty Polymers, Milan, Italy, a commercially available, anionic, segmented high molecular weight polyfluorourethane with perfluoropolyether groups was extensively evaluated as an alternative to PTFE for micro-porous layer hydrophobization. A change in polymer used is desirable in order to simplify the production process, both in terms of ink formulation and thermal treatment, as well as to get a higher hydrophobicity and, consequently, more efficient water management. Innovative prepared samples were compared to a PTFE-based GDM, in order to assess differences both from morphological and from an electrochemical point of view.

Importance of Ion Packing on the Dynamics of Ionic Liquids during Micropore Charging.

Science.gov (United States)

He, Yadong; Qiao, Rui; Vatamanu, Jenel; Borodin, Oleg; Bedrov, Dmitry; Huang, Jingsong; Sumpter, Bobby G

2016-01-07

Molecular simulations of the diffusion of EMIM(+) and TFSI(-) ions in slit-shaped micropores under conditions similar to those during charging show that in pores that accommodate only a single layer of ions, ions diffuse increasingly faster as the pore becomes charged (with diffusion coefficients even reaching ∼5 × 10(-9) m(2)/s), unless the pore becomes very highly charged. In pores wide enough to fit more than one layer of ions, ion diffusion is slower than in the bulk and changes modestly as the pore becomes charged. Analysis of these results revealed that the fast (or slow) diffusion of ions inside a micropore during charging is correlated most strongly with the dense (or loose) ion packing inside the pore. The molecular details of the ions and the precise width of the pores modify these trends weakly, except when the pore is so narrow that the ion conformation relaxation is strongly constrained by the pore walls.

Adsorption of pharmaceuticals to microporous activated carbon treated with potassium hydroxide, carbon dioxide, and steam.

Science.gov (United States)

Fu, Heyun; Yang, Liuyan; Wan, Yuqiu; Xu, Zhaoyi; Zhu, Dongqiang

2011-01-01

Adsorption of sulfapyridine, tetracycline, and tylosin to a commercial microporous activated carbon (AC) and its potassium hydroxide (KOH)-, CO-, and steam-treated counterparts (prepared by heating at 850°C) was studied to explore efficient adsorbents for the removal of selected pharmaceuticals from water. Phenol and nitrobenzene were included as additional adsorbates, and nonporous graphite was included as a model adsorbent. The activation treatments markedly increased the specific surface area and enlarged the pore sizes of the mesopores of AC (with the strongest effects shown on the KOH-treated AC). Adsorption of large-size tetracycline and tylosin was greatly enhanced, especially for the KOH-treated AC (more than one order of magnitude), probably due to the alleviated size-exclusion effect. However, the treatments had little effect on adsorption of low-size phenol and nitrobenzene due to the predominance of micropore-filling effect in adsorption and the nearly unaffected content of small micropores causative to such effect. These hypothesized mechanisms on pore-size dependent adsorption were further tested by comparing surface area-normalized adsorption data and adsorbent pore size distributions with and without the presence of adsorbed antibiotics. The findings indicate that efficient adsorption of bulky pharmaceuticals to AC can be achieved by enlarging the adsorbent pore size through suitable activation treatments. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Modelling drug flux through microporated skin.

Science.gov (United States)

Rzhevskiy, Alexey S; Guy, Richard H; Anissimov, Yuri G

2016-11-10

A simple mathematical equation has been developed to predict drug flux through microporated skin. The theoretical model is based on an approach applied previously to water evaporation through leaf stomata. Pore density, pore radius and drug molecular weight are key model parameters. The predictions of the model were compared with results derived from a simple, intuitive method using porated area alone to estimate the flux enhancement. It is shown that the new approach predicts significantly higher fluxes than the intuitive analysis, with transport being proportional to the total pore perimeter rather than area as intuitively anticipated. Predicted fluxes were in good general agreement with experimental data on drug delivery from the literature, and were quantitatively closer to the measured values than those derived from the intuitive, area-based approach. Copyright © 2016 Elsevier B.V. All rights reserved.

A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

KAUST Repository

Chang, Y.-H.; Chen, S.-C.; Wang, T.-J.; Guo, J.

2018-01-01

Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non

Synthesis and Characterization of a Novel Microporous Dihydroxyl-Functionalized Triptycene-Diamine-Based Polyimide for Natural Gas Membrane Separation.

Science.gov (United States)

Alaslai, Nasser; Ma, Xiaohua; Ghanem, Bader; Wang, Yingge; Alghunaimi, Fahd; Pinnau, Ingo

2017-09-01

An intrinsically microporous polyimide is synthesized in m-cresol by a one-pot high-temperature condensation reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and newly designed 2,6 (7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH). The 6FDA-DAT1-OH polyimide is thermally stable up to 440 °C, shows excellent solubility in polar solvents, and has moderately high Brunauer-Teller-Emmett (BET) surface area of 160 m 2 g -1 , as determined by nitrogen adsorption at -196 °C. Hydroxyl functionalization applied to the rigid 3D triptycene-based diamine building block results in a polyimide that exhibits moderate pure-gas CO 2 permeability of 70 Barrer combined with high CO 2 /CH 4 selectivity of 50. Mixed-gas permeation studies demonstrate excellent plasticization resistance of 6FDA-DAT1-OH with impressive performance as potential membrane material for natural gas sweetening with a CO 2 permeability of 50 Barrer and CO 2 /CH 4 selectivity of 40 at a typical natural gas well partial pressure of 10 atm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emulsion preparation for novel micro-porous polymeric hemi-shells

CSIR Research Space (South Africa)

Naidoo, Kersch

2008-01-01

Full Text Available -dichloromethane (DCM) oil phase , micro-porous hemi-shells formed as solvent evaporated. CO2 gas ) 252–254 www.elsevier.com/locate/matlet Polycaprolactone hemi-shells were prepared by using an O/W technique. PCL (15% w/v) was fully dissolved in 10ml DCM (oil 253K...-averaged particle size and hemi-shell yield with solvent evaporation time. (ImageJ, NIH), the number-average particle size and yield of hemi-shells were obtained with increasing time intervals (n=200). Scanning electron microscopy (LEO 1525 field emis- sion SEM...

Design of porphyrin-based conjugated microporous polymers with enhanced singlet oxygen productivity

Czech Academy of Sciences Publication Activity Database

Hynek, Jan; Rathouský, Jiří; Demel, Jan; Lang, Kamil

2016-01-01

Roč. 6, č. 50 (2016), s. 44279-44287 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : Conjugated microporous polymers * Crystalline materials * Metal organic framework * biomimetic catalysis Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 3.108, year: 2016

Highly selective and stable carbon dioxide uptake in polyindole-derived microporous carbon materials.

Science.gov (United States)

Saleh, Muhammad; Tiwari, Jitendra N; Kemp, K Christain; Yousuf, Muhammad; Kim, Kwang S

2013-05-21

Adsorption with solid sorbents is considered to be one of the most promising methods for the capture of carbon dioxide (CO₂) from power plant flue gases. In this study, microporous carbon materials used for CO₂ capture were synthesized by the chemical activation of polyindole nanofibers (PIF) at temperatures from 500 to 800 °C using KOH, which resulted in nitrogen (N)-doped carbon materials. The N-doped carbon materials were found to be microporous with an optimal adsorption pore size for CO₂ of 0.6 nm and a maximum (Brunauer-Emmett-Teller) BET surface area of 1185 m(2) g(-1). The PIF activated at 600 °C (PIF6) has a surface area of 527 m(2) g(-1) and a maximum CO₂ storage capacity of 3.2 mmol g(-1) at 25 °C and 1 bar. This high CO₂ uptake is attributed to its highly microporous character and optimum N content. Additionally, PIF6 material displays a high CO₂ uptake at low pressure (1.81 mmol g(-1) at 0.2 bar and 25 °C), which is the best low pressure CO₂ uptake reported for carbon-based materials. The adsorption capacity of this material remained remarkably stable even after 10 cycles. The isosteric heat of adsorption was calculated to be in the range of 42.7-24.1 kJ mol(-1). Besides the excellent CO₂ uptake and stability, PIF6 also exhibits high selectivity values for CO₂ over N₂, CH₄, and H₂ of 58.9, 12.3, and 101.1 at 25 °C, respectively, and these values are significantly higher than reported values.

Synthesis, Characterization and Ion Exchange of New Na/Nb/M4+/O/ H2O(M=Ti,Zr) Phases

International Nuclear Information System (INIS)

Nenoff, Tina M.; Nyman, May

1999-01-01

Due to the vast diversity of chemical media in which metal separations are executed, a wide range of ion separation materials are employed. This results in an ongoing effort to discover new phases with novel ion exchange properties. We present here the synthesis of a novel class of thermally and chemically stable microporous, niobate-based materials. Ion exchange studies show these new phases are highly selective for Sr 2+ and other bivalent metals

A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

KAUST Repository

Chang, Y.-H.

2018-02-26

Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

Gas sorption properties of microporous metal organic frameworks

International Nuclear Information System (INIS)

Lee, JeongYong; Li Jing; Jagiello, Jacek

2005-01-01

A low-temperature gas sorption study has been carried out on four three-dimensional microporous metal organic framework (MMOF) structures and two two-dimensional layered structures. The pore characteristics are analyzed based on the argon adsorption-desorption isotherms at 87 K. The results from hydrogen sorption experiments conducted at 77 and 87 K show that all MMOFs have a relatively high hydrogen uptake, with adsorbed hydrogen densities falling in the range of liquid hydrogen. Isosteric heats of hydrogen adsorption data calculated based on the Clausius-Clapeyron equation are consistent with these observations, indicating strong sorbent-sorbate interactions. - Graphical abstract: Hydrogen adsorption isotherms measured at 77 and 87 K

H{sub 2} storage in microporous materials: a comparison between zeolites and Mos

Energy Technology Data Exchange (ETDEWEB)

Ricchiardi, G.; Regli, L.; Vitillo, J. G.; Cocina, D.; Bordiga, S.; Lamberti, C.; Spoto, G.; Zecchina, A.; Bjorgen, M.; Lillerud, K. P.

2005-07-01

One of the main concerns about a hydrogen-based energy economy is the efficient storage and transport of this highly flammable gas. Many strategies have been followed or suggested in recent years to solve this problem. The most important ones are: 1) storage in metals and alloys; 2) storage in complex hydrides (alanates, borides); 3) storage by trapping in clathrates (ice and others); 4) storage in microporous materials (carbons, zeolitic materials, metal-organic frameworks, polymers). [1, 2] In this work we have focused our attention on microporous materials, where the crucial point is the strength of the interaction between the molecular hydrogen and the internal surfaces of micropores and/ or of cages of entrapping materials. It is known from fundamental studies that H2 strongly interacts with ions in the gas but that the presence of counterions decreases the interaction energy substantially. The most prominent class of microporous materials, which contains isolated and exposed cations, are zeolites and zeotypes: ideal systems to investigate the interaction of H2 with both dispersive and electrostatic forces [3]. So, even if they are not sufficiently light to represent the final solution to H2 storage, the availability of a large variety of frameworks and chemical compositions combined with low cost and superior mechanical and thermal stabilities increases the interest in these materials. In this work we have studied in detail, by means of volumetric and spectroscopic measurements, zeolites with CHA topology (as they are characterized by a strong acidity and by a big surface area). H-SSZ-13 zeolite, characterized by a low Al content (Si/Al = 11), has shown the best properties in hydrogen storage in respect to all the other zeolites and zeotypes with different compositions and topologies [4]. The results have been compared with those obtained for MOF-5 [5], a well known Metal-Organic Framework, indicated as a very good material for molecular hydrogen storage [6

Microporous carbonaceous adsorbents for CO2 separation via selective adsorption

KAUST Repository

Zhao, Yunfeng

2015-01-01

Selective adsorption of CO2 has important implications for many energy and environment-related processes, which require the separation of CO2 from other gases (e.g. N2 and CH4) with high uptakes and selectivity. The development of high-performance adsorbents is one of the most promising solutions to the success of these processes. The present review is focused on the state-of-the-art of carbon-based (carbonaceous) adsorbents, covering microporous inorganic carbons and microporous organic polymers, with emphasis on the correlation between their textural and compositional properties and their CO2 adsorption/separation performance. Special attention is given to the most recently developed materials that were not covered in previous reviews. We summarize various effective strategies (N-doping, surface functionalization, extra-framework ions, molecular design, and pore size engineering) for enhancing the CO2 adsorption capacity and selectivity of carbonaceous adsorbents. Our discussion focuses on CO2/N2 separation and CO2/CH4 separation, while including an introduction to the methods and criteria used for evaluating the performance of the adsorbents. Critical issues and challenges regarding the development of high-performance adsorbents as well as some overlooked facts and misconceptions are also discussed, with the aim of providing important insights into the design of novel carbonaceous porous materials for various selective adsorption based applications. This journal is © The Royal Society of Chemistry.

Induction of bone ingrowth with a micropore bioabsorbable suture anchor in rotator cuff tear: an experimental study in a rabbit model.

Science.gov (United States)

Kang, Yun Gyeong; Kim, Jung-Han; Shin, Jung-Woog; Baik, Jong-Min; Choo, Hye-Jung

2013-11-01

The bioabsorbable suture anchor is probably one of the most commonly used tools in arthroscopic shoulder operations. However, there is controversy about whether the bioabsorbable anchor is replaced by bone. The object of this study is to evaluate bone ingrowth into the micropore bioabsorbable suture anchor and the differences in the biomechanical properties of a micropore anchor and a nonpore anchor. A total of 16 microsized holes (diameter, 250 ± 50 μm; depth, 0.2 mm) were made on the bioabsorbable anchors with a microdrill. Twelve adult New Zealand White rabbits were randomly divided into two groups: group A (n = 6), the nonpore bioabsorbable suture anchor group, and group pA (n = 6), the micropore bioabsorbable suture anchor group. Microcomputed tomography was used at 4 and 8 weeks postoperatively to evaluate ingrowth by bone volume fraction (BVF), which was measured by calculating the ratio of the total volume of bone ingrowth to that of the region of interest. For pullout strength testing, 3 additional rabbits (6 limbs) were used for mechanical testing. The mean BVF was higher in group pA (0.288 ± 0.054) than in group A (0.097 ± 0.006). The micropore anchor had a higher pullout strength (0.520 ± 0.294 N) than the nonpore anchor (0.275 ± 0.064 N). Micropore bioabsorbable suture anchors induced bone ingrowth and showed higher pullout strength, despite processing. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Cyclic voltammetric analysis of C 1-C 4 alcohol electrooxidations with Pt/C and Pt-Ru/C microporous electrodes

Science.gov (United States)

Lee, Choong-Gon; Umeda, Minoru; Uchida, Isamu

The effect of temperature on methanol, ethanol, 2-propanol, and 2-butanol electrooxidation is investigated with Pt/C and Pt-Ru/C microporous electrodes. Cyclic voltammetry is employed in temperatures ranging from 25 to 80 °C to provide quantitative and qualitative information on the kinetics of alcohol oxidation. Methanol displays the greatest activity atom alcohols. The addition of ruthenium reduces the poisoning effect, although it is ineffective with secondary alcohols. Secondary alcohols undergo a different oxidation mechanism at higher temperatures. Microporous electrodes provide detailed information on alcohol oxidation.

Microporous silica prepared by organic templating: relationship between the molecular template and pore structure

International Nuclear Information System (INIS)

Brinker, C. Jeffrey; Cao, Guozhong; Kale, Rahul P.; Lopez, Gabriel P.; Lu, Yunfeng; Prabakar, S.

1999-01-01

Microporous silica materials with a controlled pore size and a narrow pore size distribution have been prepared by sol-gel processing using an organic-templating approach. Microporous networks were formed by pyrolytic removal of organic ligands (methacryloxypropyl groups) from organic/inorganic hybrid materials synthesized by copolymerization of 3-methacryloxypropylsilane (MPS) and tetraethoxysilane (TEOS). Molecular simulations and experimental measurements were conducted to examine the relationship between the microstructural characteristics of the porous silica (e.g., pore size, total pore volume, and pore connectivity) and the size and amount of organic template ligands added. Adsorption measurements suggest that the final porosity of the microporous silica is due to both primary pores (those present in the hybrid materials prior to pyrolysis) and secondary pores (those created by pyrolytic removal of organic templates). Primary pores were inaccessible to N(sub 2) at 77 K but accessible to CO(sub 2) at 195 K; secondary pores were accessible to both N(sub 2) (at 77 K) and CO(sub 2) (at 195 K) in adsorption measurements. Primary porosity decreases with the amount of organic ligands added because of the enhanced densification of MPS/TEOS hybrid materials as the mole fraction of trifunctional MPS moieties increases. pore volumes measured by nitrogen adsorption experiments at 77 K suggest that the secondary (template-derived) porosity exhibits a percolation behavior as the template concentration is increased. Gas permeation experiments indicate that the secondary pores are approximately 5(angstrom) in diameter, consistent with predictions based on molecular simulations

Modeling water flux and salt rejection of mesoporous γ-alumina and microporous organosilica membranes

NARCIS (Netherlands)

Farsi, A.; Boffa, V.; Qureshi, H.F.; Nijmeijer, Arian; Winnubst, Aloysius J.A.; Lykkegaard Christensen, M.

2014-01-01

The water and ion transport through a mesoporous γ-alumina membrane and a microporous organosilica membrane was simulated using the extended Nernst Planck equation combined with models for Donnan, steric and dielectric interfacial exclusion mechanisms. Due to the surface charge within the pore, the

Evaluation of procedures for estimation of the isosteric heat of adsorption in microporous materials

NARCIS (Netherlands)

Krishna, R.

2014-01-01

The major objective of this communication is to evaluate procedures for estn. of the isosteric heat of adsorption, Qst, in microporous materials such as zeolites, metal org. frameworks (MOFs)​, and zeolitic imidazolate frameworks (ZIFs)​. For this purpose we have carefully analyzed published exptl.

Micropore analysis of polymer networks by gas sorption and 129Xe NMR spectroscopy: toward a better understanding of intrinsic microporosity.

Science.gov (United States)

Weber, Jens; Schmidt, Johannes; Thomas, Arne; Böhlmann, Winfried

2010-10-05

The microporosity of two microporous polymer networks is investigated in detail. Both networks are based on a central spirobifluorene motif but have different linker groups, namely, imide and thiophene units. The microporosity of the networks is based on the "polymers of intrinsic microporosity (PIM)" design strategy. Nitrogen, argon, and carbon dioxide were used as sorbates in order to analyze the microporosity in greater detail. The gas sorption data was analyzed with respect to important parameters such as specific surface area, pore volume, and pore size (distribution). It is shown that the results can be strongly model dependent and swelling effects have to be regarded. (129)Xe NMR was used as an independent technique for the estimation of the average pore size of the polymer networks. The results indicate that both networks are mainly ultramicroporous (pore sizes microporous matter might have a different micropore size in the solvent swollen/filled state that in the dry state.

New Mixed Conductivity Mechanisms in the Cold Plasma Device Based on Silver-Modified Zeolite Microporous Electronic Materials

Science.gov (United States)

Koç, Sevgul Ozturk; Galioglu, Sezin; Ozturk, Seckin; Kurç, Burcu Akata; Koç, Emrah; Salamov, Bahtiyar G.

2018-02-01

We have analyzed the interaction between microdischarge and microporous zeolite electronic materials modified by silver (Ag0) nanoparticles (resistivity 1011 to 106 Ω cm) on the atmospheric pressure cold plasma generation in air. The generation and maintenance of stable cold plasma is studied according to the effect of the Ag0 nanoparticles. The role of charge carriers in mixed conductivity processes and electrical features of zeolite from low pressure to atmospheric pressure is analyzed in air microplasmas for both before and after breakdown regimes. The results obtained from the experiments indicate that Ag0 nanoparticles play a significant role in considerably reducing the breakdown voltage in plasma electronic devices with microporous zeolite electronic materials.

A sulfur–microporous carbon composite positive electrode for lithium/sulfur and silicon/sulfur rechargeble batteries

Directory of Open Access Journals (Sweden)

Takuya Takahashi

2015-12-01

Full Text Available Sulfur is an advantageous material as a promising next-generation positive electrode material for high-energy lithium batteries due to a high theoretical capacity of 1672 mA h g−1 although its discharge potential is somewhat modest: ca. 2 V vs Li/Li+. However, a sulfur positive electrode has some crucial problems for practical use, which are mainly attributed to the dissolution of its intermediate products in charge–discharge processes. In order to resolve the dissolution problem of lithium polysulfide, we attempted to synthesize a sulfur–microporous activated carbon (AC composite positive electrode. Moreover, we have systematically researched the battery performance of sulfur–microporous AC positive electrode with variations of electrolytes as well as negative electrodes, and found its promising positive electrode performance for a next-generation rechargeable battery.

Neutrophil-endothelial cell interactions on endothelial monolayers grown on micropore filters.

Science.gov (United States)

Taylor, R F; Price, T H; Schwartz, S M; Dale, D C

1981-01-01

We have developed a technique for growing endothelial monolayers on micropore filters. These monolayers demonstrate confluence by phase and electron microscopy and provide a functional barrier to passage of radiolabeled albumin. Neutrophils readily penetrate the monolayer in response to chemotaxin, whereas there is little movement in the absence of chemotaxin. This system offers unique advantages over available chemotaxis assays and may have wider applications in the study of endothelial function. Images PMID:7007441

Ordered hierarchical mesoporous/microporous carbon derived from mesoporous titanium-carbide/carbon composites and its electrochemical performance in supercapacitor

Energy Technology Data Exchange (ETDEWEB)

Liu, Hai-Jing; Wang, Jie; Wang, Cong-Xiao; Xia, Yong-Yao [Department of Chemistry and Shanghai Key Laboratory of Molecular, Catalysis and Innovative Materials, Institute of New Energy, Fudan University, Shanghai (China)

2011-11-15

Novel ordered hierarchical mesoporous/microporous carbon (OHMMC) derived from mesoporous titanium-carbide/carbon composites was prepared for the first time by synthesizing ordered mesoporous nanocrystalline titanium-carbide/carbon composites, followed by chlorination of titanium carbides. The mesostructure and microstructure can be conveniently tuned by controlling the TiC contents of mesoporous TiC/C composite precursor, and chlorination temperature. By optimal condition, the OHMMC has a high surface area (1917 m{sup 2}g{sup -1}), large pore volumes (1.24 cm{sup 3}g{sup -1}), narrow mesopore-size distributions (centered at about 3 nm), and micropore size of 0.69 and 1.25 nm, and shows a great potential as electrode for supercapacitor applications: it exhibits a high capacitance of 146 Fg{sup -1} in noaqueous electrolyte and excellent rate capability. The ordered mesoporous channel pores are favorable for retention and immersion of the electrolyte, providing a more favorable path for electrolyte penetration and transportation to achieve promising rate capability performance. Meanwhile, the micropores drilled on the mesopore-walls can increase the specific surface area to provide more sites for charge storage. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

Directory of Open Access Journals (Sweden)

Kunquan Li

Full Text Available Cotton-stalk activated carbon fibers (CSCFs with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area. Keywords: Cotton stalk, Nitrogen content, Electrode, Surface area, Methylene blue

Finite element simulation of a novel composite light-weight microporous cladding panel

Science.gov (United States)

Tian, Lida; Wang, Dongyan

2018-04-01

A novel composite light-weight microporous cladding panel with matched connection detailing is developed. Numerical simulation on the experiment is conducted by ABAQUS. The accuracy and rationality of the finite element model is verified by comparison between the simulation and the experiment results. It is also indicated that the novel composite cladding panel is of desirable bearing capacity, stiffness and deformability under out-of-plane load.

Graft-copolymerization of polyethersulfone microporous membrane with electron beam simultaneous irradiation method

International Nuclear Information System (INIS)

Han Zhaolei; Meng Fanxia; Wang Yongxia; Liu Xiaoguang; Wang Rong

2010-01-01

Polyethersulfone(PES) microporous membrane was grafted with methacrylic acid under electron beam irradiation. Controlling the monomer concentration or the absorbed dose, the relationships of the degree of grafting with the monomer concentration and the absorbed dose were obtained for optimum the monomer concentration and absorbed dose. The grafted membrane was characterized by FT-IR and SEM, and the hydrophilicity contact angle of the membrane was tested. (authors)

Calorimetry by immersion into liquid nitrogen and liquid argon: a better way to determine the internal surface area of micropores.

Science.gov (United States)

Navarrete, Ricardo; Llewellyn, Philip; Rouquerol, Françoise; Denoyel, Renaud; Rouquerol, Jean

2004-09-15

The aim of this work is to assess the internal surface area of a set of samples (either carbons or oxides, either porous or nonporous, either microporous or mesoporous) by microcalorimetry via immersion into liquid nitrogen or argon. We have made use of an isothermal, heat-flux microcalorimeter, initially designed and built in our laboratory for the sake of gas adsorption experiments at 77 or 87 K. It seems that immersion calorimetry into liquid nitrogen and argon makes it possible to go one step further in the determination of the internal surface area of micropores.

High-performance carbon molecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide

KAUST Repository

Salinas, Octavio; Ma, Xiaohua; Litwiller, Eric; Pinnau, Ingo

2015-01-01

An intrinsically microporous polymer with hydroxyl functionalities, PIM-6FDA-OH, was used as a precursor for various types of carbon molecular sieve (CMS) membranes for ethylene/ethane separation. The pristine polyimide films were heated under

Superior capture of CO2 achieved by introducing extra-framework cations into N-doped microporous carbon

KAUST Repository

Zhao, Yunfeng; Liu, Xin; Yao, Kexin; Zhao, Lan; Han, Yu

2012-01-01

We designed and prepared a novel microporous carbon material (KNC-A-K) for selective CO2 capture. The combination of a high N-doping concentration (>10 wt %) and extra-framework cations, which were introduced into carbonaceous sorbents

A refined surgical treatment modality for bromhidrosis: Subcutaneous scissor with micropore.

Science.gov (United States)

Dai, Yeqin; Xu, Ai-E; He, Junhua

2017-05-01

Axillary bromhidrosis has a strong negative effect on one's social life. A high success rate and few complications are criteria for a surgical treatment. The objective of this study was to evaluate a new surgical treatment modality for bromhidrosis: subcutaneous scissor with micropore. Twenty patients with bromhidrosis were treated. Patients were placed in a supine position with their treated arms abducted to 110°. After injection of 60 mL of tumescent solution into each axilla, one small incision was made at the middle axillary of the hair-bearing area. The whole hair-bearing skin was undermined at the level of the superficial fat to obtain adequate skin eversion. The flaps were everted to offer full exposure of the apocrine glands, and meticulous excision of each gland was performed. Both sides were punctured with scalpel. The micropore was used for drainage, and whose width was just 3 mm. Finally, the incisions were re-approximated, and bulky compressive dressings were applied to the area for 72 hours. Of the 40 axillae (20 patients), 34 (85.0%) showed excellent results, and six (15.0%) had good results. Malodor was significantly decreased. There were no serious complications. This technique can produce excellent results with a lower complication rate than most other surgical modalities and can be performed without costly equipment. © 2017 Wiley Periodicals, Inc.

Fabrication of a micro-porous Ti–Zr alloy by electroless reduction with a calcium reductant for electrolytic capacitor applications

International Nuclear Information System (INIS)

Kikuchi, Tatsuya; Yoshida, Masumi; Taguchi, Yoshiaki; Habazaki, Hiroki; Suzuki, Ryosuke O.

2014-01-01

Highlights: • A metallic Ti–Zr alloy was obtained by electroless reduction for capacitor applications. • The reduction mechanisms were studied by SEM, XRD, EPMA, and an oxygen analyzer. • The alloy was obtained by electroless reduction in the presence of excess calcium reductant. • A micro-porous Ti–Zr alloy was successfully obtained. • The alloy has a low oxygen content and a large surface area. -- Abstract: A metallic titanium and zirconium micro-porous alloy for electrolytic capacitor applications was produced by electroless reduction with a calcium reductant in calcium chloride molten salt at 1173 K. Mixed TiO 2 –70 at%ZrO 2 oxides, metallic calcium, and calcium chloride were placed in a titanium crucible and heated under argon atmosphere to reduce the oxides with the calcium reductant. A metallic Ti–Zr alloy was obtained by electroless reduction in the presence of excess calcium reductant and showed a micro-porous morphology due to the sintering of each of the reduced particles during the reduction. The residual oxygen content and surface area of the reduced Ti–Zr alloy decreased over time during the electroless reduction. The element distributions were slightly different at the positions of the alloy and were in the composition range of Ti-69.3 at% to 74.3 at%Zr. A micro-porous Ti–Zr alloy with low oxygen content (0.20 wt%) and large surface area (0.55 m 2 g −1 ) was successfully fabricated by electroless reduction under optimal conditions. The reduction mechanisms of the mixed and pure oxides by the calcium reductant are also discussed

A superhard sp3 microporous carbon with direct bandgap

Science.gov (United States)

Pan, Yilong; Xie, Chenlong; Xiong, Mei; Ma, Mengdong; Liu, Lingyu; Li, Zihe; Zhang, Shuangshuang; Gao, Guoying; Zhao, Zhisheng; Tian, Yongjun; Xu, Bo; He, Julong

2017-12-01

Carbon allotropes with distinct sp, sp2, and sp3 hybridization possess various different properties. Here, a novel all-sp3 hybridized tetragonal carbon, namely the P carbon, was predicted by the evolutionary particle swarm structural search. It demonstrated a low density among all-sp3 carbons, due to the corresponding distinctive microporous structure. P carbon is thermodynamically stable than the known C60 and could be formed through the single-walled carbon nanotubes (SWCNTs) compression. P carbon is a direct bandgap semiconductor displaying a strong and superhard nature. The unique combination of electrical and mechanical properties constitutes P carbon a potential superhard material for semiconductor industrial fields.

Highly microporous carbons derived from a complex of glutamic acid and zinc chloride for use in supercapacitors

Science.gov (United States)

Dong, Xiao-Ling; Lu, An-Hui; He, Bin; Li, Wen-Cui

2016-09-01

The selection of carbon precursor is an important factor when designing carbon materials. In this study, a complex derived from L-glutamic acid and zinc chloride was used to prepare highly microporous carbons via facile pyrolysis. L-glutamic acid, a new carbon precursor with nitrogen functionality, coordinated with zinc chloride resulted in a homogeneous distribution of Zn2+ on the molecular level. During pyrolysis, the evaporation of the in situ formed zinc species creates an abundance of micropores together with the inert gases. The obtained carbons exhibit high specific surface area (SBET: 1203 m2 g-1) and a rich nitrogen content (4.52 wt%). In excess of 89% of the pore volume consists of micropores with pore size ranging from 0.5 to 1.2 nm. These carbons have been shown to be suitable for use as supercapacitor electrodes, and have been tested in 6 M KOH where a capacitance of 217 F g-1 was achieved at a current density of 0.5 A g-1. A long cycling life of 30 000 cycles was achieved at a current density of 1 A g-1, with only a 9% loss in capacity. The leakage current through a two-electrode device was measured as 2.3 μA per mg of electrode and the self-discharge characteristics were minimal.

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

Science.gov (United States)

He, Yuanzhen; Cheng, Hefa

2016-05-01

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

Inhibition of neutrophil migration by aggregated immunoglobulin attached to micropore membranes.

Science.gov (United States)

Kemp, A S; Brown, S

1980-01-01

The effect of substrate-bound immunoglobulin on neutrophil migration was examined. Immunoglobulin aggregates bound to micropore membranes inhibited the neutrophil response to a chemotactic stimulus. This inhibition was reversed by the presence of aggregates in suspension suggesting competition between substrate-bound and free aggregates for neutrophil surface binding sites. The immobilization of neutrophils by substrate-bound aggregated immunoglobulin suggests a mechanism for the accumulation of neutrophils at sites of immune complex deposition and tissue-bound antibodies in vivo. PMID:7380477

The use of expanded microporous polytetrafluoroethylene for limb salvage: a preliminary report.

Science.gov (United States)

Campbell, C D; Brooks, D H; Webster, M W; Bahnson, H T

1976-05-01

Initial laboratory and clinical evaluations of a new prosthetic material, expanded microporous polytetrafluoroethylene (PTFE), for small vessel replacement is promising and encourages further clinical trial. Frequently the autogenous saphenous vein is not available for bypass procedures, and alternative arterial substitutes have not proved reliable for replacement of small vessels. In this study, 15 patients with impending loss of limb and no available saphenous vein underwent revascularization of the lower extremity with expanded microporous PTFE grafts. Thirteen of 15 patients now demonstrate viable extremities with a resulting over-all early patency and limb salvage rate of 87 percent for this series. Follow-up ranges from one to 8 months. Seven patients had diabetes mellitus and eight had atherosclerotic heart disease. Nine grafts crossed the knee joint. In all patients arterial runoff was poor. Six patients had previous femoropopliteal bypasses, five with autogenous veins and one with Dacron velour. Two patients had multiple previous operations that failed, first with autogenous vein and later with fabric grafts. The current limb salvage and patency rate of 87 percent in high-risk patients suggests that expanded PTFE may be the prosthesis of choice when an autogenous vein is not available and possibly an equally good substitute when the venous autograft is available.

The function of microporous layers and the interaction between the anode and cathode in DMFCs

DEFF Research Database (Denmark)

Zhang, H. F.; Wang, SY; Pei, PC

2008-01-01

A combined effect of microporous layers (MPLs) on direct methanol fuel cells (DMFCs) is investigated. From the distribution of the outstanding carbon loading combinations of the cathode MPL and anode MPL as well as the evolutions of polarization curves, a combined effect in which the contributions...

Cyclic voltammetric analysis of C{sub 1}-C{sub 4} alcohol electrooxidations with Pt/C and Pt-Ru/C microporous electrodes

Energy Technology Data Exchange (ETDEWEB)

Lee, Choong-Gon [Department of Chemical Engineering, Hanbat National University, San 16-1 Dukmyung-dong, Yusong-gu, Daejon (Korea); Umeda, Minoru [Department of Chemistry, Nagaoka University of Technology, Kamitomioka, Nagaoka (Japan); Uchida, Isamu [Department of Applied Chemistry, Tohoku University, Aramaki-aoba, Aoba-ku, Sendai (Japan)

2006-09-29

The effect of temperature on methanol, ethanol, 2-propanol, and 2-butanol electrooxidation is investigated with Pt/C and Pt-Ru/C microporous electrodes. Cyclic voltammetry is employed in temperatures ranging from 25 to 80{sup o}C to provide quantitative and qualitative information on the kinetics of alcohol oxidation. Methanol displays the greatest activity atom alcohols. The addition of ruthenium reduces the poisoning effect, although it is ineffective with secondary alcohols. Secondary alcohols undergo a different oxidation mechanism at higher temperatures. Microporous electrodes provide detailed information on alcohol oxidation. (author)

Positively charged microporous ceramic membrane for the removal of Titan Yellow through electrostatic adsorption.

Science.gov (United States)

Cheng, Xiuting; Li, Na; Zhu, Mengfu; Zhang, Lili; Deng, Yu; Deng, Cheng

2016-06-01

To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane. The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421L/(m(2)·hr) under the trans-membrane pressure of 0.03bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10mg/L between pH3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater. Copyright © 2016. Published by Elsevier B.V.

ZnO template strategy for the synthesis of 3D interconnected graphene nanocapsules from coal tar pitch as supercapacitor electrode materials

Science.gov (United States)

He, Xiaojun; Li, Xiaojing; Ma, Hao; Han, Jiufeng; Zhang, Hao; Yu, Chang; Xiao, Nan; Qiu, Jieshan

2017-02-01

3D interconnected graphene nanocapsules (GNCs) were prepared from diverse aromatic hydrocarbons by a nano-ZnO-template strategy coupled with in-situ KOH activation technique. The as-made graphene networks feature thin carbonaceous shells with well-balanced micropores and mesopores. Such 3D porous networks provide freeways for good electron conduction, short pores for ion fast transport, and abundant micropores for ion adsorption. As the electrodes in supercapacitors, the unique 3D GNCs show a high capacitance of 277 F g-1 at 0.05 A g-1, a good rate performance of 194 F g-1 at 20 A g-1, and an excellent cycle stability with over 97.4% capacitance retention after 15000 cycles in 6 M KOH electrolyte. This synthesis strategy paves a universal way for mass production of 3D graphene materials from diverse aromatic hydrocarbon sources including coal tar pitch and petroleum pitch for high performance supercapacitors as well as support and sorbent.

X-ray absorption spectroscopic studies on novel microporous copper containing catalytic systems

International Nuclear Information System (INIS)

Bhargava, Suresh K.; Akolekar, Deepak B.; Foran, Garry

2006-01-01

Novel copper metal modified microporous aluminosilicate and aluminophosphate catalysts with the high phase purity were synthesized and characterized. CuK-edge XAS measurements were carried out over a series of copper containing SAPO-34 and ZSM-5 catalysts. EXAFS technique was used to obtain specific climacteric information related to the copper atomic distances, coordination and near neighbour environments. EXAFS studies indicated the presence of different of Cu species on ZSM-5/SAPO34 catalysts

Microporous gel electrolytes based on amphiphilic poly(vinylidene fluoride-co-hexafluoropropylene) for lithium batteries

International Nuclear Information System (INIS)

Yu Shicheng; Chen Lie; Chen Yiwang; Tong Yongfen

2012-01-01

Poly(vinylidene fluoride-co-hexafluoropropylene) grafted poly(poly(ethylene glycol) methyl ether methacrylate) (PVDF-HFP-g-PPEGMA) is simply prepared by single-step synthesis directly via atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) from poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Thermal, mechanical, swelling and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, are evaluated and the effects of the various contents and average molecular weights of PEGMA on those properties are also been investigated. By phase inversion technique, the copolymer membranes tend to form well-defined microporous morphology with the increase of content and average molecular weight of PEGMA, due to the competition and cooperation between the hydrophilic PEGMA segments and hydrophobic PVDF-HFP. When these membranes are gelled with 1 M LiCF 3 SO 3 in ethylene carbonate (EC)/propylene carbonate (PC) (1:1, v/v), their saturated electrolyte uptakes (up to 323.5%) and ion conductivities (up to 2.01 × 10 -3 S cm -1 ) are dramatically improved with respect to the pristine PVDF-HFP, ascribing to the strong affinity of the hydrophilic PEGMA segments with the electrolytes. All the polymer electrolytes are electrochemically stable up to 4.7 V versus Li/Li + , and show good mechanical properties. Coin cells based on the polymer electrolytes show stable charge-discharge cycles and deliver discharge capacities to LiFePO 4 is up to 156 mAh g -1 .

Comparison of adsorption of Remazol Black B and Acidol Red on microporous activated carbon felt.

Science.gov (United States)

Donnaperna, L; Duclaux, L; Gadiou, R; Hirn, M-P; Merli, C; Pietrelli, L

2009-11-15

The adsorption of two anionic dyes, Remazol Black B (RB5) and Acidol Red 2BE-NW (AR42), onto a microporous activated carbon felt was investigated. The characterization of carbon surface chemistry by X-ray microanalysis, Boehm titrations, and pH-PZC measurements indicates that the surface oxygenated groups are mainly acidic. The rate of adsorption depends on the pH and the experimental data fit the intraparticle diffusion model. The pore size distribution obtained by DFT analysis shows that the mean pore size is close to 1nm, which indicates that a slow intraparticle diffusion process control the adsorption. The adsorption isotherms were measured for different pH values. The Khan and the Langmuir-Freundlich models lead to the best agreement with experimental data for RB5 and AR42, respectively. These isotherm simulations and the pH dependence of adsorption show that the adsorption capacity is mainly controlled by nondispersive electrostatic interactions for pH values below 4. The adsorption kinetics, the irreversibility of the process, and the influence of the pH indicate that the rate of adsorption in this microporous felt proceeds through two steps. The first one is fast and results from direct interaction of dye molecules with the external surface of the carbon material (which account for 10% of the whole surface area); in the second, slow step, the adsorption rate is controlled by the slow diffusion of dye molecules into the narrow micropores. The influence of temperature on the adsorption isotherms was studied and the thermodynamic parameters were obtained. They show that the process is spontaneous and exothermic.

Potential application of microporous structured poly(vinylidene fluoride-hexafluoropropylene)/poly(ethylene terephthalate) composite nonwoven separators to high-voltage and high-power lithium-ion batteries

International Nuclear Information System (INIS)

Jeong, Hyun-Seok; Choi, Eun-Sun; Kim, Jong Hun; Lee, Sang-Young

2011-01-01

Highlights: → Microporous-structured PVdF-HFP/PET composite nonwoven separators for Li-batteries. → Well-developed microporous structure and liquid electrolyte wettability. → Provision of facile ion transport and suppressed growth of cell impedance. → Superior cell performance at high-voltages/high-current densities. - Abstract: We demonstrate potential application of a new composite non-woven separator, which is comprised of a phase inversion-controlled, microporous polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) gel polymer electrolyte and a polyethylene terephthalate (PET) non-woven support, to high-voltage and high-power lithium-ion batteries. In comparison to a commercialized polyethylene (PE) separator, the composite non-woven separator exhibits distinct improvements in microporous structure and liquid electrolyte wettability. Based on the understanding of the composite non-woven separator, cell performances of the separator at challenging charge/discharge conditions are investigated and discussed in terms of ion transport of the separator and AC impedance of the cell. The aforementioned advantageous features of the composite non-woven separator play a key role in providing facile ion transport and suppressing growth of cell impedance during cycling, which in turn contribute to superior cell performances at harsh charge/discharge conditions such as high voltages and high current densities.

Discrimination of methanol and ethanol vapors by the use of a single optical sensor with a microporous sensitive layer.

Science.gov (United States)

Kieser, Birgit; Dieterle, Frank; Gauglitz, Günter

2002-09-15

The sorption of methanol and ethanol vapors by a microporous glassy polycarbonate is studied. The increase of the refractive index of the polymer during analyte sorption is measured by surface plasmon resonance. Both analytes are sorbed into the micropores of the polymer showing different diffusion kinetics. The sensor response during analyte exposure is subdivided into different time channels. By evaluating this additional data dimension by neural networks, a simultaneous multicomponent analysis of binary mixtures of ethanol and methanol vapors is possible using the sensor response of only one single sensor. A feature extraction results in an interpretable model and an improved prediction with errors of 2.0% for methanol and 2.4% for ethanol.

Synthesis of hydrophobic zeolite X-SiO{sub 2} core-shell composites

Energy Technology Data Exchange (ETDEWEB)

Liu Liying [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China); Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Singh, Ranjeet; Li Gang; Xiao Gongkui [Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Department of Chemical Engineering, Monash University, Clayton, Victoria 3800 (Australia); Webley, Paul A., E-mail: paul.webley@eng.monash.edu.au [Cooperative Research Centre for Greenhouse Gas Technologies (CO-2CRC) (Australia); Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Zhai Yuchun [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China)

2012-04-16

Highlights: Black-Right-Pointing-Pointer Hydrophobic 13X zeolite composites with silicalite and mesoporous silica shells are designed. Black-Right-Pointing-Pointer These core-shell composites are silynated and their hydrophobicity is tested. Black-Right-Pointing-Pointer Addition of silica layer increases the density of surface hydroxyl groups which makes the improvement of the hydrophobicity possible by further silynation. - Abstract: Core-shell structures of zeolite X coated with silicalite as well as mesoporous (MCM-41) have been synthesized. Furthermore, the surfaces of the silicalite and mesoporous silica shells were silylated using organosilanes. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption, scanning and transmission electron microscopy. The results show that the properties of zeolite 13X-silicalite and zeolite 13X-mesoporous silica core-shells composite structures are well maintained even after the modification. As expected, the shell thickness increased with increase in synthesis time, however, the micropore volume decreased. Silylation with smaller organosilanes (trimethyl chlorosilane) resulted in decrease in surface area as they diffused through the pores; however, bulkier silane reacted with surface hydroxyl groups and maintained the pore structure. Contact angle measurements revealed that hydrophobicity of zeolite 13X was enhanced by the microporous and mesoporous shell coating and was further improved by silylation.

Synthesis and kinetics investigation of meso-microporous Cu-SAPO-34 catalysts for the selective catalytic reduction of NO with ammonia.

Science.gov (United States)

Liu, Jixing; Yu, Fuhong; Liu, Jian; Cui, Lifeng; Zhao, Zhen; Wei, Yuechang; Sun, Qianyao

2016-10-01

A series of meso-microporous Cu-SAPO-34 catalysts were successfully synthesized by a one-pot hydrothermal crystallization method, and these catalysts exhibited excellent NH 3 -SCR performance at low temperature. Their structure and physic chemical properties were characterized by means of X-ray diffraction patterns (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N 2 sorption-desorption, nuclear magnetic resonance (NMR), Inductively Coupled Plasma-Atomic Emission spectrometer (ICP-AES), X-ray absorption spectroscopy (XPS), Temperature-programmed desorption of ammonia (NH 3 -TPD), Ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS) and Temperature programmed reduction (TPR). The analysis results indicate that the high activities of Cu-SAPO-34 catalysts could be attributed to the enhancement of redox property, the formation of mesopores and the more acid sites. Furthermore, the kinetic results verify that the formation of mesopores remarkably reduces diffusion resistance and then improves the accessibility of reactants to catalytically active sites. The 1.0-Cu-SAPO-34 catalyst exhibited the high NO conversion (>90%) among the wide activity temperature window in the range of 150-425°C. Copyright © 2016. Published by Elsevier B.V.

Micropore Geometry Manipulation by Macroscopic Deformation Based on Shape Memory Effect in Porous PLLA Membrane and its Enhanced Separation Performance.

Science.gov (United States)

Zhao, Jingxin; Yang, Qiucheng; Wang, Tao; Wang, Lian; You, Jichun; Li, Yongjin

2017-12-20

An effective strategy to tailor the microporous structures has been developed based on the shape memory effect in porous poly(l-lactic acid) membranes in which tiny crystals and amorphous matrix play the roles of shape-fixed phase and reversible-phase, respectively. Our results indicate that not only PLLA membranes but micropores exhibit shape memory properties. The proportional deformations on two scales have been achieved by uniaxial or biaxial tension, providing a facile way to manipulate continuously the size and the orientation degree of pores on microscale. The enhanced separation performance has been validated by taking polystyrene colloids with varying diameters as an example.

Investigation into the Catalytic Activity of Microporous and Mesoporous Catalysts in the Pyrolysis of Waste Polyethylene and Polypropylene Mixture

Directory of Open Access Journals (Sweden)

Kaixin Li

2016-06-01

Full Text Available Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil–5 (C-ZSM-5, highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5 and β-zeolite, Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs, Kanemite-derived folded silica (KFS-16B and well-ordered Al-SBA-15 (Al-SBA-15(wo were studied with waste polyethylene (PE and polypropylene (PP mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET, X-ray powder diffraction (XRD, and NH3-temperature programmed desorption (TPD. The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2–C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

Optimization of impedance spectroscopy techniques for measuring cutaneous micropore formation after microneedle treatment in an elderly population.

Science.gov (United States)

Kelchen, Megan N; Holdren, Grant O; Farley, Matthew J; Zimmerman, M Bridget; Fairley, Janet A; Brogden, Nicole K

2014-12-01

The objective of this study was to optimize a reproducible impedance spectroscopy method in elderly subjects as a means to evaluate the effects of microneedles on aging skin. Human volunteers were treated with microneedles at six sites on the upper arm. Repeated impedance measurements were taken pre- and post-microneedle insertion. Two electrode types were evaluated (dry vs. gel), using either light or direct pressure to maintain contact between the electrode and skin surface. Transepidermal water loss (TEWL) was measured as a complementary technique. Five control subjects and nine elderly subjects completed the study. Microneedle insertion produced a significant decrease in impedance from baseline in all subjects (p micropore formation. This was supported by a complementary significant increase in TEWL (p micropore formation in elderly subjects, which will be essential for future studies describing microneedle-assisted transdermal delivery in aging populations.

Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

Energy Technology Data Exchange (ETDEWEB)

Strempfer, J., E-mail: Joerg.Strempfer@desy.de; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H. [Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22603 Hamburg (Germany); Bouchenoire, L. [XMaS, ESRF, 6 rue Jules Horowitz, BP220, Grenoble 38043 (France); Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

2016-07-27

At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L{sub 3} absorption edges are presented.

Ordered molecular arrays as templates: A new approach to synthesis of mesoporous materials

Science.gov (United States)

Behrens, P.; Stucky, G.

There has been a growing interest in the extension of the microporous molecular sieve synthesis and applications to mesoscopic dimensions. Typical areas for the application of mesoscopic zeolite-type structures are in separation (e.g., protein separation and selective adsorption of large organic molecules from waste waters) and catalysis (e.g., processing of tar sand and of the high distillates of crude oils to valuable low-boiling products). Another is in the supramolecular assembly of molecular array and polymers for electronic and optical applications. In a new concept in the synthesis of porous material the templating agent is no longer a single, solvated, organic molecule or metal ion, but rather a self-assembled molecular array. This template leads to mesoporous materials with adjustable pore sizes between 16 and greater than 100 Angstrom, covering well the mesophorous range of greatest interest. The periodic arrangement of pores is very regular, and the pore size distribution measured by absorption is nearly as sharp as that of conventional zeolites.

Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

International Nuclear Information System (INIS)

Qiu Lingguang; Gu Lina; Hu Gang; Zhang Lide

2009-01-01

Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen) 2 (H 2 O) 2 ] 2+ (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M 1 (H 2 O) 6 ].[M 2 (phen) 2 (H 2 O) 2 ] 2 .2(BTC).xH 2 O (M 1 , M 2 =Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22-24), were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed. - Grapical abstract: A modular design strategy has been developed to synthesize microporous metal-organic frameworks with potential catalytic activity by self-assembly of the framework-building blocks and the catalyst unit

Testing isotherm models and recovering empirical relationships for adsorption in microporous carbons using virtual carbon models and grand canonical Monte Carlo simulations

International Nuclear Information System (INIS)

Terzyk, Artur P; Furmaniak, Sylwester; Gauden, Piotr A; Harris, Peter J F; Wloch, Jerzy

2008-01-01

Using the plausible model of activated carbon proposed by Harris and co-workers and grand canonical Monte Carlo simulations, we study the applicability of standard methods for describing adsorption data on microporous carbons widely used in adsorption science. Two carbon structures are studied, one with a small distribution of micropores in the range up to 1 nm, and the other with micropores covering a wide range of porosity. For both structures, adsorption isotherms of noble gases (from Ne to Xe), carbon tetrachloride and benzene are simulated. The data obtained are considered in terms of Dubinin-Radushkevich plots. Moreover, for benzene and carbon tetrachloride the temperature invariance of the characteristic curve is also studied. We show that using simulated data some empirical relationships obtained from experiment can be successfully recovered. Next we test the applicability of Dubinin's related models including the Dubinin-Izotova, Dubinin-Radushkevich-Stoeckli, and Jaroniec-Choma equations. The results obtained demonstrate the limits and applications of the models studied in the field of carbon porosity characterization

Ruthenium oxide/carbon composites with microporous or mesoporous carbon as support and prepared by two procedures. A comparative study as supercapacitor electrodes

International Nuclear Information System (INIS)

Pico, F.; Morales, E.; Fernandez, J.A.; Centeno, T.A.; Ibanez, J.; Rojas, R.M.; Amarilla, J.M.; Rojo, J.M.

2009-01-01

Composites are prepared by deposition of nanoparticles of RuO 2 .xH 2 O (1-4 nm) on two carbons: microporous carbon (1.3 nm of average micropore size) and mesoporous carbon (11 nm of average mesopore size). Two-preparation procedures are used: (i) procedure A consisting of repetitive impregnations of the carbons with RuCl 3 .0.5H 2 O solutions, and (ii) procedure B based on impregnation of the carbons with Ru(acac) 3 vapour. The procedure B leads to supported RuO 2 .xH 2 O particles that appear more crystalline than those obtained by the procedure A. Specific capacitance and specific surface area of the composites are discussed as functions of the RuO 2 content, and different dependences for the composites derived from the two carbons are found. Mesoporous carbon is better support than microporous carbon. Procedure A leads to supported RuO 2 .xH 2 O particles with higher specific capacitance than the particles deposited by procedure B

Ruthenium oxide/carbon composites with microporous or mesoporous carbon as support and prepared by two procedures. A comparative study as supercapacitor electrodes

Energy Technology Data Exchange (ETDEWEB)

Pico, F. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049-Madrid (Spain); Morales, E. [Instituto de Ciencia y Tecnologia de Polimeros (ICTP), CSIC, Juan de la Cierva 3, E-28006-Madrid (Spain); Fernandez, J.A.; Centeno, T.A. [Instituto Nacional del Carbon (INCAR), CSIC, Francisco Pintado Fe 26, E-33011-Oviedo (Spain); Ibanez, J. [Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Avda. Gregorio del Amo 8, E-28040-Madrid (Spain); Rojas, R.M.; Amarilla, J.M. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049-Madrid (Spain); Rojo, J.M. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049-Madrid (Spain)], E-mail: jmrojo@icmm.csic.es

2009-03-01

Composites are prepared by deposition of nanoparticles of RuO{sub 2}.xH{sub 2}O (1-4 nm) on two carbons: microporous carbon (1.3 nm of average micropore size) and mesoporous carbon (11 nm of average mesopore size). Two-preparation procedures are used: (i) procedure A consisting of repetitive impregnations of the carbons with RuCl{sub 3}.0.5H{sub 2}O solutions, and (ii) procedure B based on impregnation of the carbons with Ru(acac){sub 3} vapour. The procedure B leads to supported RuO{sub 2}.xH{sub 2}O particles that appear more crystalline than those obtained by the procedure A. Specific capacitance and specific surface area of the composites are discussed as functions of the RuO{sub 2} content, and different dependences for the composites derived from the two carbons are found. Mesoporous carbon is better support than microporous carbon. Procedure A leads to supported RuO{sub 2}.xH{sub 2}O particles with higher specific capacitance than the particles deposited by procedure B.

Advanced Polymer Systems for Defence Applications: Power Generation, Protection and Sensing

Science.gov (United States)

2014-05-01

stacks. Fig. 9 uses two different polyimides to demonstrate the ability of that approach to reproduce both the XRD pattern and the micropore size by...Synthesis of Robust Monoliths, Oxidative Aromatization and Conversion to Microporous Carbons,” Chem. Mater. 2014, 26, 1303-1317. (c) Mahadik

Automated and inexpensive method to manufacture solid- state nanopores and micropores in robust silicon wafers

Science.gov (United States)

Vega, M.; Granell, P.; Lasorsa, C.; Lerner, B.; Perez, M.

2016-02-01

In this work an easy, reproducible and inexpensive technique for the production of solid state nanopores and micropores using silicon wafer substrate is proposed. The technique is based on control of pore formation, by neutralization etchant (KOH) with a strong acid (HCl). Thus, a local neutralization is produced around the nanopore, which stops the silicon etching. The etching process was performed with 7M KOH at 80°C, where 1.23µm/min etching speed was obtained, similar to those published in literature. The control of the pore formation with the braking acid method was done using 12M HCl and different extreme conditions: i) at 25°C, ii) at 80°C and iii) at 80°C applying an electric potential. In these studies, it was found that nanopores and micropores can be obtained automatically and at a low cost. Additionally, the process was optimized to obtain clean silicon wafers after the pore fabrication process. This method opens the possibility for an efficient scale-up from laboratory production.

Automated and inexpensive method to manufacture solid- state nanopores and micropores in robust silicon wafers

International Nuclear Information System (INIS)

Vega, M; Lasorsa, C; Lerner, B; Perez, M; Granell, P

2016-01-01

In this work an easy, reproducible and inexpensive technique for the production of solid state nanopores and micropores using silicon wafer substrate is proposed. The technique is based on control of pore formation, by neutralization etchant (KOH) with a strong acid (HCl). Thus, a local neutralization is produced around the nanopore, which stops the silicon etching. The etching process was performed with 7M KOH at 80°C, where 1.23µm/min etching speed was obtained, similar to those published in literature. The control of the pore formation with the braking acid method was done using 12M HCl and different extreme conditions: i) at 25°C, ii) at 80°C and iii) at 80°C applying an electric potential. In these studies, it was found that nanopores and micropores can be obtained automatically and at a low cost. Additionally, the process was optimized to obtain clean silicon wafers after the pore fabrication process. This method opens the possibility for an efficient scale-up from laboratory production. (paper)

Transport of radionuclides by concentrated brine in a porous medium with micropore-macropore structure

International Nuclear Information System (INIS)

Hassanizadeh, S.M.

1987-01-01

This work concerns itself with the study of effects of soil aggregation and high salt concentrations on the transport of radionuclides by concentrated brine flowing through an aggregated porous medium. The medium is considered to be composed of porous rock aggregates separated by macropores through which the brine flows and transport of salt and radionuclides takes place. The aggregates contain dead-end pores, cracks, and stationary pockets collectively called micropores. The micropore space does not contribute to the flow, but it serves as a storage for salt and radionuclides. Adsorption of radionuclides takes place at internal surfaces of aggregates where they assume that a linear equilibrium isotherm describes the process. A one-dimensional numerical model is developed which is based on two sets of equations: one set for the flow and transport of salt and another set for transport of radionuclides. Results of numerical experiments clearly indicate that the existence of high salt concentrations markedly reduces the peak of nuclides concentration and slows down their movement. Also, it is found that diffusive mass exchange between macropores and aggregates results in a pronounced lowering of the radionuclides concentration peaks. 9 references, 7 figures

Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

International Nuclear Information System (INIS)

Han Yingchao; Li Shipu; Wang Xinyu; Chen Xiaoming

2004-01-01

The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out

Recent progress in the direct synthesis of hierarchical zeolites: synthetic strategies and characterization methods

KAUST Repository

Liu, Zhaohui

2017-06-16

Hierarchically structured zeolites combine the merits of microporous zeolites and mesoporous materials to offer enhanced molecular diffusion and mass transfer without compromising the inherent catalytic activities and selectivity of zeolites. This short review gives an introduction to the synthesis strategies for hierarchically structured zeolites with emphasis on the latest progress in the route of ‘direct synthesis’ using various templates. Several characterization methods that allow us to evaluate the ‘quality’ of complex porous structures are also introduced. At the end of this review, an outlook is given to discuss some critical issues and challenges regarding the development of novel hierarchically structured zeolites as well as their applications.

Micropore clogging by leachable pyrogenic organic carbon: A new perspective on sorption irreversibility and kinetics of hydrophobic organic contaminants to black carbon.

Science.gov (United States)

Wang, Bingyu; Zhang, Wei; Li, Hui; Fu, Heyun; Qu, Xiaolei; Zhu, Dongqiang

2017-01-01

Black carbon (BC) plays a crucial role in sequestering hydrophobic organic contaminants in the environment. This study investigated key factors and mechanisms controlling nonideal sorption (e.g., sorption irreversibility and slow kinetics) of model hydrophobic organic contaminants (nitrobenzene, naphthalene, and atrazine) by rice-straw-derived BC. After removing the fraction of leachable pyrogenic organic carbon (LPyOC) (referring to composites of dissoluble non-condensed organic carbon and associated mineral components) with deionized water or 0.5 M NaOH, sorption of these sorbates to BC was enhanced. The sorption enhancement was positively correlated with sorbate molecular size in the order of atrazine > naphthalene > nitrobenzene. The removal of LPyOC also accelerated sorption kinetics and reduced sorption irreversibility. These observations were attributed to increased accessibility of BC micropores initially clogged by the LPyOC. Comparison of BC pore size distributions before and after atrazine sorption further suggested that the sorbate molecules preferred to access the micropores that were more open, and the micropore accessibility was enhanced by the removal of LPyOC. Consistently, the sorption of nitrobenzene and atrazine to template-synthesized mesoporous carbon (CMK3), a model sorbent with homogeneous pore structures, showed decreased kinetics, but increased irreversibility by impregnating sorbent pores with surface-grafted alkylamino groups and by subsequent loading of humic acid. These findings indicated an important and previously unrecognized role of LPyOC (i.e., micropore clogging) in the nonideal sorption of organic contaminants to BC. Copyright © 2016 Elsevier Ltd. All rights reserved.

N-Doped carbon spheres with hierarchical micropore-nanosheet networks for high performance supercapacitors.

Science.gov (United States)

Wang, Shoupei; Zhang, Jianan; Shang, Pei; Li, Yuanyuan; Chen, Zhimin; Xu, Qun

2014-10-18

N-doped carbon spheres with hierarchical micropore-nanosheet networks (HPSCSs) were facilely fabricated by a one-step carbonization and activation process of N containing polymer spheres by KOH. With the synergy effect of the multiple structures, HPSCSs exhibit a very high specific capacitance of 407.9 F g(-1) at 1 mV s(-1) (1.2 times higher than that of porous carbon spheres) and a robust cycling stability for supercapacitors.

Magnetic properties of Ni nanoparticles on microporous silica spheres

International Nuclear Information System (INIS)

Godsell, Jeffrey F.; Donegan, Keith P.; Tobin, Joseph M.; Copley, Mark P.; Rhen, Fernando M.F.; Otway, David J.; Morris, Michael A.; O'Donnell, Terence; Holmes, Justin D.; Roy, Saibal

2010-01-01

Ni nanoparticles (∼32 nm particle diameter) have been synthesized on the walls of microporous (∼1 nm pore diameter) silica spheres (∼2.6 μm sphere diameter) and characterised magnetically to potentially produce a new class of core (silica micro-spheres)-shell (nanometallic)-type nanocomposite material. These magnetic nanocomposite materials display a characteristic increase in coercivity with reducing temperature. The average particle size has been used to calculate the anisotropy constant for the system, K. The discussion postulates the potential mechanisms contributing to the difference between the calculated K value and the magnetocrystalline anisotropy constant of bulk Ni. Various factors such as surface anisotropy and interparticle interactions are discussed as possible contributing factors to the anisotropy values calculated in the paper.

Evaluation of cellular adhesion and organization in different microporous polymeric scaffolds.

Science.gov (United States)

Asthana, Amish; White, Charles McRae; Douglass, Megan; Kisaalita, William S

2018-03-01

The lack of prediction accuracy during drug development and screening risks complications during human trials, such as drug-induced liver injury (DILI), and has led to a demand for robust, human cell-based, in vitro assays for drug discovery. Microporous polymer-based scaffolds offer an alternative to the gold standard flat tissue culture plastic (2D TCPS) and other 3D cell culture platforms as the porous material entraps cells, making it advantageous for automated liquid handlers and high-throughput screening (HTS). In this study, we optimized the surface treatment, pore size, and choice of scaffold material with respect to cellular adhesion, tissue organization, and expression of complex physiologically relevant (CPR) outcomes such as the presence of bile canaliculi-like structures. Poly-l-lysine and fibronectin (FN) coatings have been shown to encourage cell attachment to the underlying substrate. Treatment of the scaffold surface with NaOH followed with a coating of FN improved cell attachment and penetration into pores. Of the two pore sizes we investigated (A: 104 ± 4 μm; B: 175 ± 6 μm), the larger pore size better promoted cell penetration while limiting tissue growth from reaching the hypoxia threshold. Finally, polystyrene (PS) proved to be conducive to cell growth, penetration into the scaffold, and yielded CPR outcomes while being a cost-effective choice for HTS applications. These observations provide a foundation for optimizing microporous polymer-based scaffolds suitable for drug discovery. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:505-514, 2018. © 2018 American Institute of Chemical Engineers.

Optimisation of the conditions for stripping voltammetric analysis at liquid-liquid interfaces supported at micropore arrays: a computational simulation.

Science.gov (United States)

Strutwolf, Jörg; Arrigan, Damien W M

2010-10-01

Micropore membranes have been used to form arrays of microinterfaces between immiscible electrolyte solutions (µITIES) as a basis for the sensing of non-redox-active ions. Implementation of stripping voltammetry as a sensing method at these arrays of µITIES was applied recently to detect drugs and biomolecules at low concentrations. The present study uses computational simulation to investigate the optimum conditions for stripping voltammetric sensing at the µITIES array. In this scenario, the diffusion of ions in both the aqueous and the organic phases contributes to the sensing response. The influence of the preconcentration time, the micropore aspect ratio, the location of the microinterface within the pore, the ratio of the diffusion coefficients of the analyte ion in the organic and aqueous phases, and the pore wall angle were investigated. The simulations reveal that the accessibility of the microinterfaces during the preconcentration period should not be hampered by a recessed interface and that diffusional transport in the phase where the analyte ions are preconcentrated should be minimized. This will ensure that the ions are accumulated within the micropores close to the interface and thus be readily available for back transfer during the stripping process. On the basis of the results, an optimal combination of the examined parameters is proposed, which together improve the stripping voltammetric signal and provide an improvement in the detection limit.

On the synthesis of CoAPO-46, -11 and -44 molecular sieves from a Co(Ac)2 · 4H2O· Al(iPrO)3·H3PO4 · Pr2NH·H2O gel via experimental design

NARCIS (Netherlands)

Gao, Q.; Weckhuysen, B.M.; Schoonheydt, R.A.

1999-01-01

The hydrothermal synthesis of cobalt-substituted microporous alumino-phosphates from an r[Pr2NH] ·[CoxAl1−xP1]O4 · y[H2O] gel is described. A well-defined set of experiments, based on an experimental design, was carried out in order to rationalize the influence of the crystallization

Emulsification using microporous membranes

Directory of Open Access Journals (Sweden)

Goran T. Vladisavljević

2011-10-01

Full Text Available Membrane emulsification is a process of injecting a pure dispersed phase or pre-emulsion through a microporous membrane into the continuous phase. As a result of the immiscibility of the two phases, droplets of the dispersed phase are formed at the outlets of membrane pores. The droplets formed in the process are removed from the membrane surface by applying cross-flow or stirring of the continuous phase or using a dynamic (rotating or vibrating membrane. The most commonly used membrane for emulsification is the Shirasu Porous Glass (SPG membrane, fabricated through spinodal decomposition in a melt consisting of Japanese volcanic ash (Shirasu, boric acid and calcium carbonate. Microsieve membranes are increasingly popular as an alternative to highly tortuous glass and ceramic membranes. Microsieves are usually fabricated from nickel by photolithography and electroplating or they can be manufactured from silicon nitride via Reactive Ion Etching (RIE. An advantage of microsieves compared to the SPG membrane is in much higher transmembrane fluxes and higher tolerance to fouling by the emulsion ingredients due to the existence of short, straight through pores. Unlike conventional emulsification devices such as high-pressure valve homogenisers and rotor-stator devices, membrane emulsification devices permit a precise control over the mean pore size over a wide range and during the process insignificant amount of energy is dissipated as heat. The drop size is primarily determined by the pore size, but it depends also on other parameters, such as membrane wettability, emulsion formulation, shear stress on the membrane surface, transmembrane pressure, etc.

Controlled long-term release of small peptide hormones using a new microporous polypropylene polymer: its application for vasopressin in the Brattleboro rat and potential perinatal use

International Nuclear Information System (INIS)

Kruisbrink, J.; Boer, G.J.

1984-01-01

Based on drug release by microporous hollow fibers and the recent introduction of microporous polymers, a new technique was developed for controlled delivery of peptides. Small-diameter microporous polypropylene tubing, lumen-loaded with microgram quantities of vasopressin, and coated with collodion, releases vasopressin after in vitro immersion slowly (1-100 ng/d) and constantly for months. The mechanism of pseudo-zero-order delivery is based on high adsorption of vasopressin, keeping the void volume concentration of dissolved vasopressin constant, which is consequently a constant driving force of outward diffusion. The collodion coating prevents the entry of proteinaceous compounds which would result in rapid desorption of vasopressin. The present delivery module provides a lasting release for other peptides as well (lysine-vasopressin, oxytocin, alpha-melanocyte-stimulating hormone and, to a lesser extent, Met-enkephalin). The microporous polymer-collodion device is biocompatible and, loaded with vasopressin, successfully alleviates the diabetes insipidus of Brattleboro rats deficient for vasopressin. Subcutaneous implantation normalized diuresis for a period of 60 d and constant urine vasopressin excretion is observed. When the commercially available osmotic minipump is too large for implantation, the small size of the present controlled-delivery system allows peptide treatment of young and immature laboratory rats, even if located in utero

[Study of New Micropore RF system on Lesion Formation and Complications].

Science.gov (United States)

Song, Yuwen; Xu, Xiulin; Cai, Yameng

2017-07-30

To study the safety and effectiveness of a new type of micropore ablation catheter in vitro ablation system, and to provide reference for clinical practice. To evaluate two kinds of catheter in cardiac tissue ablation depth, tissue temperature and thrombosis situation by the same RF system. The power set 25 W, There was no significant difference in ablation depth between the two groups, and no Pop and thrombosis occurred. When the power is more than 40 W, two groups occurred more Pop and thrombosis. When using high power for Cardiac RF ablation, doctors should pay more attention to complications and thrombosis.

Tissue-engineered trachea regeneration using decellularized trachea matrix treated with laser micropore technique.

Science.gov (United States)

Xu, Yong; Li, Dan; Yin, Zongqi; He, Aijuan; Lin, Miaomiao; Jiang, Gening; Song, Xiao; Hu, Xuefei; Liu, Yi; Wang, Jinpeng; Wang, Xiaoyun; Duan, Liang; Zhou, Guangdong

2017-08-01

Tissue-engineered trachea provides a promising approach for reconstruction of long segmental tracheal defects. However, a lack of ideal biodegradable scaffolds greatly restricts its clinical translation. Decellularized trachea matrix (DTM) is considered a proper scaffold for trachea cartilage regeneration owing to natural tubular structure, cartilage matrix components, and biodegradability. However, cell residual and low porosity of DTM easily result in immunogenicity and incomplete cartilage regeneration. To address these problems, a laser micropore technique (LMT) was applied in the current study to modify trachea sample porosity to facilitate decellular treatment and cell ingrowth. Decellularization processing demonstrated that cells in LMT treated samples were more easily removed compared with untreated native trachea. Furthermore, after optimizing the protocols of LMT and decellular treatments, the LMT-treated DTM (LDTM) could retain their original tubular shape with only mild extracellular matrix damage. After seeding with chondrocytes and culture in vitro for 8 weeks, the cell-LDTM constructs formed tubular cartilage with relatively homogenous cell distribution in both micropores and bilateral surfaces. In vivo results further confirmed that the constructs could form mature tubular cartilage with increased DNA and cartilage matrix contents, as well as enhanced mechanical strength, compared with native trachea. Collectively, these results indicate that LDTM is an ideal scaffold for tubular cartilage regeneration and, thus, provides a promising strategy for functional reconstruction of trachea cartilage. Lacking ideal biodegradable scaffolds greatly restricts development of tissue-engineered trachea. Decellularized trachea matrix (DTM) is considered a proper scaffold for trachea cartilage regeneration. However, cell residual and low porosity of DTM easily result in immunogenicity and incomplete cartilage regeneration. By laser micropore technique (LMT), the

Finite-element simulations of the influence of pore wall adsorption on cyclic voltammetry of ion transfer across a liquid-liquid interface formed at a micropore.

Science.gov (United States)

Ellis, Jonathan S; Strutwolf, Jörg; Arrigan, Damien W M

2012-02-21

Adsorption onto the walls of micropores was explored by computational simulations involving cyclic voltammetry of ion transfer across an interface between aqueous and organic phases located at the micropore. Micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) have been of particular research interest in recent years and show promise for biosensor and biomedical applications. The simulation model combines diffusion to and within the micropore, Butler-Volmer kinetics for ion transfer at the liquid-liquid interface, and Langmuir-style adsorption on the pore wall. Effects due to pore radius, adsorption and desorption rates, surface adsorption site density, and scan rates were examined. It was found that the magnitude of the reverse peak current decreased due to adsorption of the transferring ion on the pore wall; this decrease was more marked as the scan rate was increased. There was also a shift in the half-wave potential to lower values following adsorption, consistent with a wall adsorption process which provides a further driving force to transfer ions across the ITIES. Of particular interest was the disappearance of the reverse peak from the cyclic voltammogram at higher scan rates, compared to the increase in the reverse peak size in the absence of wall adsorption. This occurred for scan rates of 50 mV s(-1) and above and may be useful in biosensor applications using micropore-based ITIES.

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Basile, Maria Assunta; Gomez d' Ayala, Giovanna; Malinconico, Mario [Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, Pozzuoli (Naples) (Italy); Laurienzo, Paola, E-mail: paola.laurienzo@ipcb.cnr.it [Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, Pozzuoli (Naples) (Italy); Coudane, Jean; Nottelet, Benjamin [Institut des Biomolécules Max Mousseron (IBMM), Artificial Biopolymers Group, CNRS UMR 5247, University of Montpellier 1, Faculty of Pharmacy, 15 Av. C. Flahault, Montpellier 34093 (France); Ragione, Fulvio Della [Department of Biochemistry and Biophysics, Second University of Naples, Via L. De Crecchio 7, Naples (Italy); Oliva, Adriana, E-mail: adriana.oliva@unina2.it [Department of Biochemistry and Biophysics, Second University of Naples, Via L. De Crecchio 7, Naples (Italy)

2015-03-01

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent–non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions. - Graphical abstract: Functionalized PCL is used to realize nanocomposites with hydroxyapatite (HA) in the form of microporous membranes. The influence of different grafted groups on mechanical properties, in vitro degradation, porous membrane structure and interaction with mesenchymal stromal cells (MSC) is discussed. - Highlights: • Functionalized PCL shows faster in vitro degradation rate. • Functionalized PCL shows superior cell adhesion, proliferation and differentiation. • Nanocomposites based

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

International Nuclear Information System (INIS)

Basile, Maria Assunta; Gomez d'Ayala, Giovanna; Malinconico, Mario; Laurienzo, Paola; Coudane, Jean; Nottelet, Benjamin; Ragione, Fulvio Della; Oliva, Adriana

2015-01-01

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent–non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions. - Graphical abstract: Functionalized PCL is used to realize nanocomposites with hydroxyapatite (HA) in the form of microporous membranes. The influence of different grafted groups on mechanical properties, in vitro degradation, porous membrane structure and interaction with mesenchymal stromal cells (MSC) is discussed. - Highlights: • Functionalized PCL shows faster in vitro degradation rate. • Functionalized PCL shows superior cell adhesion, proliferation and differentiation. • Nanocomposites based

Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition.

Science.gov (United States)

Ogawa, Tomohiro; Ezoe, Yuichiro; Moriyama, Teppei; Mitsuishi, Ikuyuki; Kakiuchi, Takuya; Ohashi, Takaya; Mitsuda, Kazuhisa; Putkonen, Matti

2013-08-20

To enhance x-ray reflectivity of silicon micropore optics using dry etching of silicon (111) wafers, iridium coating is tested by use of atomic layer deposition. An iridium layer is successfully formed on sidewalls of tiny micropores with a pore width of 20 μm and depth of 300 μm. The film thickness is ∼20  nm. An enhanced x-ray reflectivity compared to that of silicon is confirmed at Ti Kα 4.51 keV, for what we believe to be the first time, with this type of optics. Some discrepancies from a theoretical reflectivity curve of iridium-coated silicon are noticed at small incident angles <1.3°. When a geometrical shadowing effect due to occultation by a ridge existing on the sidewalls is taken into account, the observed reflectivity becomes well represented by the modified theoretical curve. An estimated surface micro roughness of ∼1  nm rms is consistent with atomic force microscope measurements of the sidewalls.

Arcillas pilarizadas con Al-Fe y Al-Ce-Fe como sistema de postratamiento de las aguas residuales del beneficio húmedo del café

OpenAIRE

Peralta Ladino, Yury Marlén

2013-01-01

El efluente del sistema de tratamiento biológico de las aguas residuales del beneficio húmedo del café contiene compuestos no biodegradables, principalmente (ácidos hidroxicinámicos y clorogénicos) los cuales fueron identificados mediante análisis preliminares por LC-MS, por su toxicidad deben ser tratados antes de su descarga en las fuentes hídricas. El sistema Fenton heterogéneo empleando como soportes Al-Fe-PILC y Al-Ce-Fe-PILC (en polvo) mostró importantes conversión de compuestos fenólic...

An analysis of the influence of production conditions on the development of the microporous structure of the activated carbon fibres using the LBET method

Science.gov (United States)

Kwiatkowski, Mirosław

2017-12-01

The paper presents the results of the research on the application of the new analytical models of multilayer adsorption on heterogeneous surfaces with the unique fast multivariant identification procedure, together called LBET method, as a tool for analysing the microporous structure of the activated carbon fibres obtained from polyacrylonitrile by chemical activation using potassium and sodium hydroxides. The novel LBET method was employed particularly to evaluate the impact of the used activator and the hydroxide to polyacrylonitrile ratio on the obtained microporous structure of the activated carbon fibres.

Transport of Zn(OH)4(-2) ions across a polyolefin microporous membrane

Science.gov (United States)

Krejci, Ivan; Vanysek, Peter; Trojanek, Antonin

1993-04-01

Transport of ZN(OH)4(2-) ions through modified microporous polypropylene membranes (Celgard 3401, 350140) was studied using polarography and conductometry. Soluble Nafion as an ion exchange modifying agent was applied to the membrane by several techniques. The influence of Nafion and a surfactant on transport of zinc ions through the membrane was studied. A relationship between membrane impedance and the rate of Zn(OH)4(2-) transport was found. The found correlation between conductivity, ion permeability and Nafion coverage suggests a suitable technique of membrane preparation to obtain desired zinc ion barrier properties.

Enhancement of micropore filling of water on carbon black by platinum loading

Energy Technology Data Exchange (ETDEWEB)

Miyajima, Naoya, E-mail: miyajima@yamanashi.ac.jp [Interdisciplinary Graduate School of Medicine and Engineering, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan); Hatori, Hiroaki [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Radovic, Ljubisa R. [Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Yamada, Yoshio [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

2010-10-15

Two kinds of typical carbons, carbon black and activated carbon fibers, were modified with platinum nanoparticles without changing their original pore structures. The surface properties of the modified carbons were investigated by measuring of water adsorption isotherms. Micropore filling of water was facilitated by the presence of platinum nanoparticles on the surface of the carbon black. On the other hand, such a filling effect was not observed in the case of the activated carbon fibers. A critical content and/or size of platinum nanoparticles could be required to promote efficiently the water adsorption.

Enhancement of pool boiling heat transfer in water using sintered copper microporous coatings

Energy Technology Data Exchange (ETDEWEB)

Jun, Seong Chul; KIm, Jin Sub; You, Seung M. [Dept. of Mechanical Engineering, The University of Texas at Dallas, Richardson (United States); Son, Dong Gun; KIm, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-08-15

Pool boiling heat transfer of water saturated at atmospheric pressure was investigated experimentally on Cu surfaces with high-temperature, thermally-conductive, microporous coatings (HTCMC). The coatings were created by sintering Cu powders on Cu surfaces in a nitrogen gas environment. A parametric study of the effects of particle size and coating thickness was conducted using three average particle sizes (APSs) of 10 μm, 25 μm, and 67 μm and various coating thicknesses. It was found that nucleate boiling heat transfer (NBHT) and critical heat flux (CHF) were enhanced significantly for sintered microporous coatings. This is believed to have resulted from the random porous structures that appear to include reentrant type cavities. The maximum NBHT coefficient was measured to be approximately 400 kW/m2k with APS 67 μm and 296 μm coating thicknesses. This value is approximately eight times higher than that of a plain Cu surface. The maximum CHF observed was 2.1 MW/m2 at APS 67 μm and 428 μm coating thicknesses, which is approximately double the CHF of a plain Cu surface. The enhancement of NBHT and CHF appeared to increase as the particle size increased in the tested range. However, two larger particle sizes (25 μm and 67 μm) showed a similar level of enhancement.

Characterization of cellulose acetate micropore membrane immobilized acylase I.

Science.gov (United States)

Guo, Yong-Sheng; Wang, Jie; Song, Xi-Jin

2004-12-01

This paper describes an innovative method for the immobilization of acylase I, which was entrapped into the CA-CTA micropore membrane. The most suitable casting solutions proportion for immobilizing the enzyme was obtained through orthogonal experiment. Properties of the enzyme membrane were investigated and compared with those of free enzyme and blank membrane. The thermal stability and pH stability of the enzyme inside the membrane were changed by immobilization. The optimum pH was found to be 6.0, which changes 1.0 unit compared with that of free acylase I. The optimum temperature was found to be about 90 degrees C, which is higher than that of free acylase I (60 degrees C). Experimental results showed that immobilization had effects on the kinetic parameters of acylase I.

Microporous crystals and synthesis schemes

Science.gov (United States)

Tumas, William; Ott, Kevin C.; McCleskey, T. Mark; Yates, Matthew Z.; Birnbaum, Eva R.

2008-04-22

Novel zeolites are produced by combining a polar solute, a silicon or phosphorous source, and a structure directing agent. Surfactants and a hydrophobic solvent are added to the previously mixed three species and shaken to disperse the surfactants. The reverse microemulsion is stirred overnight, at about room temperature and then iced for five to ten minutes. A metal source is added vigorously shaken for about two minutes. The mixture is then aged for about two hours at about room temperature. A mineralizer is added and the resultant mixture aged for about two hours at about room temperature. The mixture is heated to about 180.degree. C., for a suitable time period. The final novel product is then isolated.

Microporous MOFs Engaged in the Formation of Nitrogen-Doped Mesoporous Carbon Nanosheets for High-Rate Supercapacitors.

Science.gov (United States)

Hou, Ya-Nan; Zhao, Zongbin; Yu, Zhengfa; Zhang, Su; Li, Shaofeng; Yang, Juan; Zhang, Han; Liu, Chang; Wang, Zhiyu; Qiu, Jieshan

2018-02-21

Nitrogen-doped mesoporous carbon nanosheets (NMCS) have been fabricated from zinc-based microporous metal-organic frameworks (ZIF-8) by pyrolysis in a molten salt medium. The as-prepared NMCS exhibit significantly improved specific capacitance (NMCS-8: 232 F g -1 at 0.5 A g -1 ) and capacitance retention ratio (75.9 % at 50 A g -1 ) compared with the micropore-dominant nitrogen-doped porous carbon polyhedrons (NPCP-5: 178 F g -1 at 0.5 A g -1 , 15.9 % at 20 A g -1 ) obtained by direct pyrolysis of nanocrystalline ZIF-8. The excellent capacitive performance and high rate performance of the NMCS can be attributed to their unique combination of structure and composition, that is, the two-dimensional and hierarchically porous structure provides a short ion-transport pathway and facilitates the supply of electrolyte ions, and the nitrogen-doped polar surface improves the interface wettability when used as an electrode. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The osteogenic capacity of biomimetic hierarchical micropore/nanorod-patterned Sr-HA coatings with different interrod spacings.

Science.gov (United States)

Zhou, Jianhong; Li, Bo; Han, Yong; Zhao, Lingzhou

2016-07-01

Advanced titanium based bone implant with fast established, rigid and stable osseointegration is stringently needed in clinic. Here the hierarchical micropore/nanorod-patterned strontium doped hydroxyapatite (Ca9Sr1(PO4)6(OH)2, Sr1-HA) coatings (MNRs) with different interrod spacings varying from about 300 to 33nm were developed. MNRs showed dramatically differential biological performance closely related to the interrod spacing. Compared to micropore/nanogranule-patterned Sr1-HA coating (MNG), MNRs with an interrod spacing of larger than 137nm resulted in inhibited in vitro mesenchymal stem cell functions and in vivo osseointegration, while those of smaller than 96nm gave rise to dramatically enhanced the biological effect, especially those of mean 67nm displayed the best effect. The differential biological effect of MNRs was related to their modulation on the focal adhesion mediated mechanotransduction. These results suggest that MNRs with a mean interrod spacing of 67nm may give rise to an advanced implant of improved clinical performance. Copyright © 2016 Elsevier Inc. All rights reserved.

A Highly Stable Microporous Covalent Imine Network Adsorbent for Natural Gas Upgrading and Flue Gas CO2 Capture

KAUST Repository

Das, Swapan Kumar; Wang, Xinbo; Ostwal, Mayur; Lai, Zhiping

2016-01-01

The feasible capture and separation of CO2 and N2 from CH4 is an important task for natural gas upgrading and the control of greenhouse gas emissions. Here, we studied the microporous covalent imine networks (CIN) material prepared through Schiff

Graphene-wrapped sulfur/metal organic framework-derived microporous carbon composite for lithium sulfur batteries

Energy Technology Data Exchange (ETDEWEB)

Chen, Renjie, E-mail: kx210@cam.ac.uk, E-mail: chenrj@bit.edu.cn; Zhao, Teng [Beijing Key Laboratory of Environmental Science and Engineering, School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing 100081 (China); Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom); Tian, Tian; Fairen-Jimenez, David [Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Cao, Shuai; Coxon, Paul R.; Xi, Kai, E-mail: kx210@cam.ac.uk, E-mail: chenrj@bit.edu.cn; Vasant Kumar, R.; Cheetham, Anthony K. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

2014-12-01

A three-dimensional hierarchical sandwich-type graphene sheet-sulfur/carbon (GS-S/C{sub ZIF8-D}) composite for use in a cathode for a lithium sulfur (Li-S) battery has been prepared by an ultrasonic method. The microporous carbon host was prepared by a one-step pyrolysis of Zeolitic Imidazolate Framework-8 (ZIF-8), a typical zinc-containing metal organic framework (MOF), which offers a tunable porous structure into which electro-active sulfur can be diffused. The thin graphene sheet, wrapped around the sulfur/zeolitic imidazolate framework-8 derived carbon (S/C{sub ZIF8-D}) composite, has excellent electrical conductivity and mechanical flexibility, thus facilitating rapid electron transport and accommodating the changes in volume of the sulfur electrode. Compared with the S/C{sub ZIF8-D} sample, Li-S batteries with the GS-S/C{sub ZIF8-D} composite cathode showed enhanced capacity, improved electrochemical stability, and relatively high columbic efficiency by taking advantage of the synergistic effects of the microporous carbon from ZIF-8 and a highly interconnected graphene network. Our results demonstrate that a porous MOF-derived scaffold with a wrapped graphene conductive network structure is a potentially efficient design for a battery electrode that can meet the challenge arising from low conductivity and volume change.

Graphene-wrapped sulfur/metal organic framework-derived microporous carbon composite for lithium sulfur batteries

Directory of Open Access Journals (Sweden)

Renjie Chen

2014-12-01

Full Text Available A three-dimensional hierarchical sandwich-type graphene sheet-sulfur/carbon (GS-S/CZIF8-D composite for use in a cathode for a lithium sulfur (Li-S battery has been prepared by an ultrasonic method. The microporous carbon host was prepared by a one-step pyrolysis of Zeolitic Imidazolate Framework-8 (ZIF-8, a typical zinc-containing metal organic framework (MOF, which offers a tunable porous structure into which electro-active sulfur can be diffused. The thin graphene sheet, wrapped around the sulfur/zeolitic imidazolate framework-8 derived carbon (S/CZIF8-D composite, has excellent electrical conductivity and mechanical flexibility, thus facilitating rapid electron transport and accommodating the changes in volume of the sulfur electrode. Compared with the S/CZIF8-D sample, Li-S batteries with the GS-S/CZIF8-D composite cathode showed enhanced capacity, improved electrochemical stability, and relatively high columbic efficiency by taking advantage of the synergistic effects of the microporous carbon from ZIF-8 and a highly interconnected graphene network. Our results demonstrate that a porous MOF-derived scaffold with a wrapped graphene conductive network structure is a potentially efficient design for a battery electrode that can meet the challenge arising from low conductivity and volume change.

Gas/vapour separation using ultra-microporous metal–organic frameworks: insights into the structure/separation relationship

KAUST Repository

Adil, Karim; Belmabkhout, Youssef; Pillai, Renjith S.; Cadiau, Amandine; Bhatt, Prashant; Assen, Ayalew Hussen Assen; Maurin, Guillaume; Eddaoudi, Mohamed

2017-01-01

The separation of related molecules with similar physical/chemical properties is of prime industrial importance and practically entails a substantial energy penalty, typically necessitating the operation of energy-demanding low temperature fractional distillation techniques. Certainly research efforts, in academia and industry alike, are ongoing with the main aim to develop advanced functional porous materials to be adopted as adsorbents for the effective and energy-efficient separation of various important commodities. Of special interest is the subclass of metal-organic frameworks (MOFs) with pore aperture sizes below 5-7 Å, namely ultra-microporous MOFs, which in contrast to conventional zeolites and activated carbons show great prospects for addressing key challenges in separations pertaining to energy and environmental sustainability, specifically materials for carbon capture and separation of olefin/paraffin, acetylene/ethylene, linear/branched alkanes, xenon/krypton, etc. In this tutorial review we discuss the latest developments in ultra-microporous MOF adsorbents and their use as separating agents via thermodynamics and/or kinetics and molecular sieving. Appreciably, we provide insights into the distinct microscopic mechanisms governing the resultant separation performances, and suggest a plausible correlation between the inherent structural features/topology of MOFs and the associated gas/vapour separation performance.

Gas/vapour separation using ultra-microporous metal–organic frameworks: insights into the structure/separation relationship

KAUST Repository

Adil, Karim

2017-05-30

The separation of related molecules with similar physical/chemical properties is of prime industrial importance and practically entails a substantial energy penalty, typically necessitating the operation of energy-demanding low temperature fractional distillation techniques. Certainly research efforts, in academia and industry alike, are ongoing with the main aim to develop advanced functional porous materials to be adopted as adsorbents for the effective and energy-efficient separation of various important commodities. Of special interest is the subclass of metal-organic frameworks (MOFs) with pore aperture sizes below 5-7 Å, namely ultra-microporous MOFs, which in contrast to conventional zeolites and activated carbons show great prospects for addressing key challenges in separations pertaining to energy and environmental sustainability, specifically materials for carbon capture and separation of olefin/paraffin, acetylene/ethylene, linear/branched alkanes, xenon/krypton, etc. In this tutorial review we discuss the latest developments in ultra-microporous MOF adsorbents and their use as separating agents via thermodynamics and/or kinetics and molecular sieving. Appreciably, we provide insights into the distinct microscopic mechanisms governing the resultant separation performances, and suggest a plausible correlation between the inherent structural features/topology of MOFs and the associated gas/vapour separation performance.

Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

International Nuclear Information System (INIS)

Darbandi, Masih; Laurent, Sophie; Busch, Martin; Li Zian; Yuan Ying; Krüger, Michael; Farle, Michael; Winterer, Markus; Vander Elst, Luce; Muller, Robert N.; Wende, Heiko

2013-01-01

Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N 2 adsorption–desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

Converting biomass waste into microporous carbon with simultaneously high surface area and carbon purity as advanced electrochemical energy storage materials

Science.gov (United States)

Sun, Fei; Wang, Lijie; Peng, Yiting; Gao, Jihui; Pi, Xinxin; Qu, Zhibin; Zhao, Guangbo; Qin, Yukun

2018-04-01

Developing carbon materials featuring both high accessible surface area and high structure stability are desirable to boost the performance of constructed electrochemical electrodes and devices. Herein, we report a new type of microporous carbon (MPC) derived from biomass waste based on a simple high-temperature chemical activation procedure. The optimized MPC-900 possesses microporous structure, high surface area, partially graphitic structure, and particularly low impurity content, which are critical features for enhancing carbon-based electrochemical process. The constructed MPC-900 symmetric supercapacitor exhibits high performances in commercial organic electrolyte such as widened voltage window up to 3 V and thereby high energy/power densities (50.95 Wh kg-1 at 0.44 kW kg-1; 25.3 Wh kg-1 at 21.5 kW kg-1). Furthermore, a simple melt infiltration method has been employed to enclose SnO2 nanocrystals onto the carbon matrix of MPC-900 as a high-performance lithium storage material. The obtained SnO2-MPC composite with ultrafine SnO2 nanocrystals delivers high capacities (1115 mAh g-1 at 0.2 A g-1; 402 mAh g-1 at 10 A g-1) and high-rate cycling lifespan of over 2000 cycles. This work not only develops a microporous carbon with high carbon purity and high surface area, but also provides a general platform for combining electrochemically active materials.

Electrolyte Engineering: Optimizing High-Rate Double-Layer Capacitances of Micropore- and Mesopore-Rich Activated Carbon.

Science.gov (United States)

Chen, Ting-Hao; Yang, Cheng-Hsien; Su, Ching-Yuan; Lee, Tai-Chou; Dong, Quan-Feng; Chang, Jeng-Kuei

2017-09-22

Various types of electrolyte cations as well as binary cations are used to optimize the capacitive performance of activated carbon (AC) with different pore structures. The high-rate capability of micropore-rich AC, governed by the mobility of desolvated cations, can outperform that of mesopore-rich AC, which essentially depends on the electrolyte conductivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-pressure argon adsorption assessment of micropore connectivities in activated carbons.

Science.gov (United States)

Zimny, T; Villieras, F; Finqueneisel, G; Cossarutto, L; Weber, J V

2006-01-01

Low-pressure argon adsorption has been used to study the energetic distribution of microporous activated carbons differing by their burn-off. The collected isotherms were analyzed using the derivative isotherm summation method. Some oscillations on the experimental curves for very low partial pressures were detected. The results are analyzed and discussed according to the literature and could be attributed to local overheating caused by spontaneous mass transfer of argon through constrictions between former pores and the new opening pore or deadend pores. We used the dynamic character of the experimental method and mainly the discrepancy of the quasi-equilibrium state to deduce key parameters related to the porosity topology.

Production of carbon nanotubes: Chemical vapor deposition synthesis from liquefied petroleum gas over Fe-Co-Mo tri-metallic catalyst supported on MgO

Energy Technology Data Exchange (ETDEWEB)

Setyopratomo, P., E-mail: puguh-sptm@yahoo.com; Wulan, Praswasti P. D. K., E-mail: wulanmakmur@gmail.com; Sudibandriyo, M., E-mail: msudib@che.ui.ac.id [Chemical Engineering Department, University of Indonesia, Depok Campus, Depok 16424 (Indonesia)

2016-06-03

Carbon nanotubes were produced by chemical vapor deposition method to meet the specifications for hydrogen storage. So far, the various catalyst had been studied outlining their activities, performances, and efficiencies. In this work, tri-metallic catalyst consist of Fe-Co-Mo supported on MgO was used. The catalyst was prepared by wet-impregnation method. Liquefied Petroleum Gas (LPG) was used as carbon source. The synthesis was conducted in atmospheric fixed bed reactor at reaction temperature range 750 – 850 °C for 30 minutes. The impregnation method applied in this study successfully deposed metal component on the MgO support surface. It found that the deposited metal components might partially replace Mg(OH){sub 2} or MgO molecules in their crystal lattice. Compare to the original MgO powder; it was significant increases in pore volume and surface area has occurred during catalyst preparation stages. The size of obtained carbon nanotubes is ranging from about 10.83 nm OD/4.09 nm ID up to 21.84 nm OD/6.51 nm ID, which means that multiwall carbon nanotubes were formed during the synthesis. Yield as much as 2.35 g.CNT/g.catalyst was obtained during 30 minutes synthesis and correspond to carbon nanotubes growth rate of 0.2 μm/min. The BET surface area of the obtained carbon nanotubes is 181.13 m{sup 2}/g and around 50 % of which is contributed by mesopores. Micropore with half pore width less than 1 nm contribute about 10% volume of total micro and mesopores volume of the carbon nanotubes. The existence of these micropores is very important to increase the hydrogen storage capacity of the carbon nanotubes.

Characterization of natural microporous metal-oxides: the case of todorokite ([Mn2+,Ca,Mg]Mn4+3O7.H2O)

International Nuclear Information System (INIS)

Godelitsas, A.; Misaelides, P; Katranas, T.; Klewe-Nebenius, H.; Triantafyllidis, C.; Pavlidou, E.; Anousis, I.

1998-01-01

Todorokite is a naturally occurring hydrous Mn-oxide exhibiting a complicated chemical composition. It shows a referred unusual crystal structure characterized by the presence of micropores (tunnels) with a free aperture of 0.69 x 0.69 nm and therefore exceptional physicochemical properties. In order to define the compositional and structural characteristics of the mineral and especially its physicochemical properties. For this purpose a number of characterization techniques were used including XRD, SEM-EDS, XRF, AAS, FT-IR, XPS, TPD, Z-potential measurements and TG/TDA combined with micro-porosimetry. The obtained results were compared to relevant ones concerning other natural microporous materials (e.g. clays, zeolites, micas) and were used to predict potential applications of the material.(author)

Pillared-layer microporous metal-organic frameworks constructed by robust hydrogen bonds. Synthesis, characterization, and magnetic and adsorption properties of 2,2'-biimidazole and carboxylate complexes.

Science.gov (United States)

Ding, Bing-Bing; Weng, Yan-Qin; Mao, Zong-Wan; Lam, Chi-Keung; Chen, Xiao-Ming; Ye, Bao-Hui

2005-11-28

Two new isostructural complexes [M(H2biim)3][M(btc)(Hbiim)].2H2O (M = Co, (1); M = Ni, (2)) (btc = 1,3,5-benzenetricarboxylate; H2biim = 2,2'-biimidazole) have been synthesized and characterized by single-crystal X-ray diffraction. They present a unique structure consisting of two distinct units: the monomeric cations [M(H2biim)3]2+ and the two-dimensional (2D) anionic polymer [M(Hbiim)(btc)]2-. In the anionic moiety, the Hbiim- monoanion is simultaneously coordinated to one metal atom in a bidentate mode and further to another metal atom in a monodentate mode. The imidazolate groups bridge the two adjacent metal ions into a helical chain which is further arranged in left- and right-handed manners. These chains are bridged by btc ligands into a 2D brick wall structure. The most interesting aspect is that the [M(H2biim)3]2+ cations act as pillars and link the anionic layers via robust heteromeric hydrogen-bonded synthons (9) and (7) formed by the uncoordinated oxygen atoms of carboxylate groups and the H2biim ligands, resulting in a microporous metal-organic framework with one-dimensional (1D) channels (ca. 11.85 angstroms x 11.85 angstroms for 1 and 11.43 angstroms x 11.43 angstroms for 2). Magnetic properties of these two complexes have also been studied in the temperature range of 2-300 K, and their magnetic susceptibilities obey the Curie-Weiss law in the temperature range of 20-300 K (for 1) and 2-300 K (for 2), respectively, showing anti-ferromagnetic coupling through imidazolate bridging. Taking into consideration the Heisenberg infinite chain model as well as the possibility of chain-to-chain and chain-to-cation interactions, the anti-ferromagnetic exchange of 2 is analyzed via a correction for the molecular field, giving the values of g(cat) = 2.296, g(Ni) = 2.564, J = -13.30 cm(-1), and zJ' = -0.017 cm(-1). The microporous frameworks are stable at ca. 350 degrees C. They do not collapse after removal of the guest water molecules in the channels, and they

Micropore-free surface-activated carbon for the analysis of polychlorinated dibenzo-p-dioxins-dibenzofurans and non-ortho-substituted polychlorinated biphenyls in environmental samples.

Science.gov (United States)

Kemmochi, Yukio; Tsutsumi, Kaori; Arikawa, Akihiro; Nakazawa, Hiroyuki

2002-11-22

2,3,7,8-Substituted polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and non-ortho-substituted polychlorinated biphenyls (PCBs) account for almost all of the total toxic equivalents (TEQ) in environmental samples. Activated carbon columns are used to fractionate the samples for GC-MS analysis or bioassay. Micropore-free surface-activated carbon is highly selective for PCDD/Fs and non-ortho-PCBs and can improve the conventional activated carbon column clean-up. Along with sulfuric acid-coated diatomaceous earth columns, micropore-free surface-activated carbon provides a rapid, robust, and high-throughput sample preparation method for PCDD/Fs and non-ortho-PCBs analysis.

Catalytic Properties of 3D Graphene-Like Microporous Carbons Synthesized in a Zeolite Template

Czech Academy of Sciences Publication Activity Database

Sazama, Petr; Pastvová, Jana; Rizescu, C.; Tirsoaga, A.; Parvulescu, V. I.; Garcia, H.; Kobera, Libor; Seidel, J.; Rathouský, Jiří; Klein, Petr; Jirka, Ivan; Morávková, Jaroslava; Blechta, Václav

2018-01-01

Roč. 8, č. 3 (2018), s. 1779-1789 ISSN 2155-5435 R&D Projects: GA ČR GA15-12113S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : catalytic hydrogenation * zeolite-templated carbon * 3D graphene-like microporous carbons Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 10.614, year: 2016

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers

International Nuclear Information System (INIS)

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang Zhen; Takano, Takayuki; Maeda, Ryutaro

2006-01-01

To develop x-ray mirrors for micropore optics, smooth silicon (111)sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 μm wide (111) sidewalls was fabricated using a 220 μm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time,x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers.

Science.gov (United States)

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang, Zhen; Takano, Takayuki; Maeda, Ryutaro

2006-12-10

To develop x-ray mirrors for micropore optics, smooth silicon (111) sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 microm wide (111) sidewalls was fabricated using a 220 microm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time, x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

Forced intrusion of water and aqueous solutions in microporous materials: from fundamental thermodynamics to energy storage devices.

Science.gov (United States)

Fraux, Guillaume; Coudert, François-Xavier; Boutin, Anne; Fuchs, Alain H

2017-12-07

We review the high pressure forced intrusion studies of water in hydrophobic microporous materials such as zeolites and MOFs, a field of research that has emerged some 15 years ago and is now very active. Many of these studies are aimed at investigating the possibility of using these systems as energy storage devices. A series of all-silica zeolites (zeosil) frameworks were found suitable for reversible energy storage because of their stability with respect to hydrolysis after several water intrusion-extrusion cycles. Several microporous hydrophobic zeolite imidazolate frameworks (ZIFs) also happen to be quite stable and resistant towards hydrolysis and thus seem very promising for energy storage applications. Replacing pure water by electrolyte aqueous solutions enables to increase the stored energy by a factor close to 3, on account of the high pressure shift of the intrusion transition. In addition to the fact that aqueous solutions and microporous silica materials are environmental friendly, these systems are thus becoming increasingly interesting for the design of new energy storage devices. This review also addresses the theoretical approaches and molecular simulations performed in order to better understand the experimental behavior of nano-confined water. Molecular simulation studies showed that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional and sufficiently open. In an extreme confinement situations such as in ferrierite zeosil, condensation seem to take place through a continuous supercritical crossing from a diluted to a dense fluid, on account of the fact that the first-order transition line is shifted to higher pressure, and the confined water critical point is correlatively shifted to lower temperature. These molecular simulation studies suggest that the most important features of the intrusion/extrusion process can be understood in terms of equilibrium

Copolyimide mixed matrix membranes with oriented microporous titanosilicate JDF-L1sheet particles

OpenAIRE

Galve, Alejandro; Vispe, Eugenio; Téllez, Carlos; Coronas, Joaquín

2011-01-01

JDF-L1 is a microporous titanosilicate exhibiting a layer structure with pore size of about 3 Å. It is consequently an attractive material to separate H2-containing mixtures. This is the reason why JDF-L1, after disaggregation by means of hexadecyltrimethylammonium surfactant, has been combined with a carboxyl group containing copolyimide (6FDA-4MPD/6FDA-DABA 4:1) to produce mixed matrix membranes, which were applied to the separation of H2/CH4 and O2/N2 mixtures. Additionally, due to the she...

NATO Advanced Research Workshop: Application of Natural Microporous Materials to the Environmental Technology. Book of Abstracts

International Nuclear Information System (INIS)

1998-01-01

In this proceedings About 80 people from Albania, Belgium, Bulgaria, Czech Republic, Estonia, Germany, Greece, Italy, Poland, Portugal, Romania, Russia, Spain, U.K., Turkey, Ukraine, U.S.A. and Slovakia took part in the workshop. 56 reports had been presented. from which 19 reports deals with the scope of INIS. The purpose of the workshop was the critical assessment of the current developments in the field of utilization of natural microporous materials (zeolites, clays, oxides) for the solution of problems related to the toxic and nuclear waste management, the water pollution control and decontamination, the environmental catalysis associated to the atmospheric pollution, the creation of new materials for energy storage and agricultural management including the development of artificial soils for plant growth in the space. Of especial importance for this meeting was the exchange of information and know-how among specialists working in institutions of NATO and Cooperation Partner countries aiming in the development of common strategies for the solution of environmental problems and the promotion of the further scientific and technological collaboration. Nineteen papers deals with the using of microporous materials for separation of radionuclides

Highly selective sieving of small gas molecules by using an ultra-microporous metal–organic framework membrane

KAUST Repository

Kang, Zixi; Xue, Ming; Fan, Lili; Huang, Lin; Guo, Lijia; Wei, Guoying; Chen, Banglin; Qiu, Shilun

2014-01-01

© 2014 The Royal Society of Chemistry. Two tailor-made microporous metal-organic framework (MOF) membranes were successfully fabricated on nickel screens by secondary growth. The effect of pore structures on gas separation was examined by means of single and binary gas permeation tests. The MOF JUC-150 membrane with its ultra-micropores showed marked preferential permeance to H2 relative to other gas molecules. The selectivity factors of this membrane were 26.3, 17.1 and 38.7 for H2/CH4, H2/N2 and H2/CO2, respectively, at room temperature. To the best of our knowledge, these values represent unprecedentedly high separation selectivity among those for all MOF membranes reported to date. The JUC-150 membrane also shows high thermal stability and outstanding separation performance at a high temperature of 200 °C. The separation performance of these membranes persists even after more than 1 year exposure to air. The superiority of the tailored pore size, high selectivity for H2 over other gases, significant stability and recyclability make these materials potential candidates for industrial H2 recycling applications.

Highly selective sieving of small gas molecules by using an ultra-microporous metal–organic framework membrane

KAUST Repository

Kang, Zixi

2014-09-12

© 2014 The Royal Society of Chemistry. Two tailor-made microporous metal-organic framework (MOF) membranes were successfully fabricated on nickel screens by secondary growth. The effect of pore structures on gas separation was examined by means of single and binary gas permeation tests. The MOF JUC-150 membrane with its ultra-micropores showed marked preferential permeance to H2 relative to other gas molecules. The selectivity factors of this membrane were 26.3, 17.1 and 38.7 for H2/CH4, H2/N2 and H2/CO2, respectively, at room temperature. To the best of our knowledge, these values represent unprecedentedly high separation selectivity among those for all MOF membranes reported to date. The JUC-150 membrane also shows high thermal stability and outstanding separation performance at a high temperature of 200 °C. The separation performance of these membranes persists even after more than 1 year exposure to air. The superiority of the tailored pore size, high selectivity for H2 over other gases, significant stability and recyclability make these materials potential candidates for industrial H2 recycling applications.

The antibacterial activity of ceramsite coated by silver nanoparticles in micropore.

Science.gov (United States)

Qiu, Shan; Huang, Xu; Xu, Shanwen; Ma, Fang

2015-05-01

In the present study, ceramsite was combined with silver nanoparticles (AgNPs) to fabricate a new nanocomposite for water disinfection. The ceramsite was prepared by fly ash, straw ash, and cement. AgNPs were synthesized using polyvinylpyrrolidone (PVP) as the capping agent. The nanocomposite was prepared by self-aggregation of AgNPs on the surface of the ceramsite. AgNPs capped with PVP can form a thin film on the surface of micropore in ceramsite. The nanocomposite can inhibit bacteria growth and induce damage of the cell membrane of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Therefore, the nanocomposite is a new material which can be used for disinfection in drinking water.

Laser Control of Self-Organization Process in Microscopic Region and Fabrication of Fine Microporous Structure

OpenAIRE

Matsumura, Yukimasa; Inami, Wataru; Kawata, Yoshimasa

2012-01-01

We present a controlling technique of microporous structure by laser irradiation during self-organization process. Self-organization process is fabrication method of microstructure. Polymer solution was dropped on the substrate at high humid condition. Water in air appears dropping air temperature below the dew point. The honeycomb structure with regularly aligned pores on the film was fabricated by attaching water droplets onto the solution surface. We demonstrate that it was possible to pre...

Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

International Nuclear Information System (INIS)

Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang.

1996-01-01

Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer

Interfacial micropore defect formation in PEDOT:PSS-Si hybrid solar cells probed by TOF-SIMS 3D chemical imaging.

Science.gov (United States)

Thomas, Joseph P; Zhao, Liyan; Abd-Ellah, Marwa; Heinig, Nina F; Leung, K T

2013-07-16

Conducting p-type polymer layers on n-type Si have been widely studied for the fabrication of cost-effective hybrid solar cells. In this work, time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to provide three-dimensional chemical imaging of the interface between poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) and SiOx/Si in a hybrid solar cell. To minimize structural damage to the polymer layer, an Ar cluster sputtering source is used for depth profiling. The present result shows the formation of micropore defects in the interface region of the PEDOT:PSS layer on the SiOx/Si substrate. This interfacial micropore defect formation becomes more prominent with increasing thickness of the native oxide layer, which is a key device parameter that greatly affects the hybrid solar cell performance. Three-dimensional chemical imaging coupled with Ar cluster ion sputtering has therefore been demonstrated as an emerging technique for probing the interface of this and other polymer-inorganic systems.

Switchable transport strategy to deposit active Fe/Fe3C cores into hollow microporous carbons for efficient chromium removal.

Science.gov (United States)

Liu, Dong-Hai; Guo, Yue; Zhang, Lu-Hua; Li, Wen-Cui; Sun, Tao; Lu, An-Hui

2013-11-25

Magnetic hollow structures with microporous shell and highly dispersed active cores (Fe/Fe3 C nanoparticles) are rationally designed and fabricated by solution-phase switchable transport of active iron species combined with a solid-state thermolysis technique, thus allowing selective encapsulation of functional Fe/Fe3 C nanoparticles in the interior cavity. These engineered functional materials show high loading (≈54 wt%) of Fe, excellent chromium removal capability (100 mg g(-1)), fast adsorption rate (8766 mL mg(-1) h(-1)), and easy magnetic separation property (63.25 emu g(-1)). During the adsorption process, the internal highly dispersed Fe/Fe3 C nanoparticles supply a driving force for facilitating Cr(VI) diffusion inward, thus improving the adsorption rate and the adsorption capacity. At the same time, the external microporous carbon shell can also efficiently trap guest Cr(VI) ions and protect Fe/Fe3 C nanoparticles from corrosion and subsequent leaching problems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of nanocomposite powders of calcium phosphate/titanium oxide for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Delima, S.A.; Camargo, N.H.A.; Souza, J.C.P.; Gemelli, E., E-mail: sarahamindelima@hotmail.com, E-mail: dem2nhac@joinville.udesc.br, E-mail: souzajulio@joinville.udesc.br, E-mail: gemelli@joinville.udesc.br [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

2009-07-01

The nanostructured bioceramics of calcium phosphate are current themes of research and they are becoming important as bone matrix in regeneration of tissues in orthopedic and dental applications. Nanocomposite powders of calcium phosphate, reinforced with nanometric particles of titanium oxide, silica oxide and alumina oxid ealpha, are being widely studied because they offer new microstructures, nanostructures and interconnected microporosity with high superficial area of micropores that contribute to osteointegration and osteoinduction processes. This study is about the synthesis of nanocomposites powders of calcium phosphate reinforced with 1%, 2%, 3% and 5% in volume of titanium oxide and its characterization through the techniques of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis (DTA), Thermogravimetry (TG) and Dilatometry. (author)

Synthesis and characterization of nanocomposite powders of calcium phosphate/titanium oxide for biomedical applications

International Nuclear Information System (INIS)

Delima, S.A.; Camargo, N.H.A.; Souza, J.C.P.; Gemelli, E.

2009-01-01

The nanostructured bioceramics of calcium phosphate are current themes of research and they are becoming important as bone matrix in regeneration of tissues in orthopedic and dental applications. Nanocomposite powders of calcium phosphate, reinforced with nanometric particles of titanium oxide, silica oxide and alumina oxid ealpha, are being widely studied because they offer new microstructures, nanostructures and interconnected microporosity with high superficial area of micropores that contribute to osteointegration and osteoinduction processes. This study is about the synthesis of nanocomposites powders of calcium phosphate reinforced with 1%, 2%, 3% and 5% in volume of titanium oxide and its characterization through the techniques of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis (DTA), Thermogravimetry (TG) and Dilatometry. (author)

Preparation of poly(acrylonitrile-butyl acrylate) gel electrolyte for lithium-ion batteries

International Nuclear Information System (INIS)

Tian Zheng; He Xiangming; Pu Weihua; Wan Chunrong; Jiang Changyin

2006-01-01

Poly(acrylonitrile-butyl acrylate) gel polymer electrolyte was prepared for lithium ion batteries. The preparation started with synthesis of poly(acrylonitrile-butyl acrylate) by radical emulsion polymerization, followed by phase inversion to produce microporous membrane. Then, the microporous gel polymer electrolytes (MGPEs) was prepared with the microporous membrane and LiPF 6 in ethylene carbonate/diethyl carbonate. The dry microporous membrane showed a fracture strength as high as 18.98 MPa. As-prepared gel polymer electrolytes presented ionic conductivity in excess of 3.0 x 10 -3 S cm -1 at ambient temperature and a decomposition voltage over 6.6 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for Li-ion batteries

Microporous poly(acrylonitrile-methyl methacrylate) membrane as a separator of rechargeable lithium battery

International Nuclear Information System (INIS)

Zhang, S.S.; Ervin, M.H.; Xu, K.; Jow, T.R.

2004-01-01

We studied microporous poly(acrylonitrile-methyl methacrylate), AMMA, membrane as the separator of Li/LiMn 2 O 4 cell. The porous AMMA membrane was prepared by the phase inversion method with N,N-dimethylformamide (DMF) as the solvent and water as the non-solvent. We observed that morphology of the resulting membrane was strongly affected by the concentration of polymer solution: low concentration produced finger-like pores with dense skin on two surfaces of the membrane, while high concentration yielded open voids with dense layer on the other surface of the membrane. Regardless of their morphology, both membranes could be rapidly wetted by the liquid electrolyte (1.0 m LiBF 4 dissolved in 1:3 wt.% mixture of ethylene carbonate (EC) and γ-butyrolactone (GBL)), and could be swollen at elevated temperatures, which resulted in the formation of a microporous gel electrolyte (MGE). It was shown that the resulting MGE not only had high ionic conductivity and but also had good compatibility with metal lithium even at 60 deg. C. Cyclic voltammetric test showed that the MGE had an electrochemical window of 4.9 V versus Li + /Li. At room temperature, the Li/MGE/LiMn 2 O 4 cell showed excellent cycliability with a specific capacity of 121-125 mA h g -1 LiMn 2 O 4 . It was shown that even at 60 deg. C good mechanical strength of the MGE remained. Therefore, the MGE is suitable for the application of battery separator at elevated temperatures

Effects of textural and surface characteristics of microporous activated carbons on the methane adsorption capacity at high pressures

International Nuclear Information System (INIS)

Bastos-Neto, M.; Canabrava, D.V.; Torres, A.E.B.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.; Azevedo, D.C.S.; Cavalcante, C.L.

2007-01-01

The objective of this study is to relate textural and surface characteristics of selected microporous activated carbons to their methane storage capacity. In this work, a magnetic suspension balance (Rubotherm, Germany) was used to measure methane adsorption isotherms of several activated carbon samples. Textural characteristics were assessed by nitrogen adsorption on a regular surface area analyzer (Autosorb-MP, by Quantachrome, USA). N 2 adsorption was analysed by conventional models (BET, DR, HK) and by Monte Carlo molecular simulations. Elemental and surface analyses were performed by X-ray photoelectronic spectroscopy (XPS) for the selected samples. A comparative analysis was then carried out with the purpose of defining some correlation among the variables under study. For the system under study, pore size distribution and micropore volume seem to be a determining factor as long as the solid surface is perfectly hydrophobic. It was concluded that the textural parameters per se do not unequivocally determine natural gas storage capacities. Surface chemistry and methane adsorption equilibria must be taken into account in the decision-making process of choosing an adsorbent for gas storage

Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

International Nuclear Information System (INIS)

Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

2012-01-01

Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

Importance of Micropore-Mesopore Interfaces in Carbon Dioxide Capture by Carbon-Based Materials.

Science.gov (United States)

Durá, Gema; Budarin, Vitaliy L; Castro-Osma, José A; Shuttleworth, Peter S; Quek, Sophie C Z; Clark, James H; North, Michael

2016-08-01

Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

EXPERIMENTAL STUDY ON THE GAS-LIQUID FLOW IN THE MEMBRANE MICROPORE AERATION BIOREACTOR

Directory of Open Access Journals (Sweden)

DONG LIU

2008-12-01

Full Text Available Particle Image Velocimetry (PIV has been developed to measure the typical two-phase flow of various work conditions in Membrane Micropore Aeration Bioreactor (MMAB. The fluid phase is separated out using image processing techniques, which provides accurate measurements for the Bioreactor’s flow field, and makes it possible for quantitative analysis of the momentum exchange, heat exchange and the process of micro-admixture. The experimental method PIV used in this paper can preferably measure the complex flow in the reactor and initiates a new approach for the bioreactor design which mainly depends on experience at present.

Microporous polyethylene separators — today and tomorrow. Separator development trends for modern automotive batteries

Science.gov (United States)

Böhnstedt, Werner

During the past decade, the design of modern automotive batteries has undergone a fundamental change. The introduction of microporous polyethylene pocket separators has resulted in an approximately 8% better volume utilization. Besides increasing the energy density, the polyethylene envelope has enalbed an improvement in cold-cranking performance and has raised the production efficiency. A first failure-mode analysis of pocket-separated automotive batteries in Europe with respect to leaf separation is presented. For comparable service life, a shift in failure mode has been found. Although corrosion of the positive electrode still dominates, a significant increase in positive active-material shedding is noted. This is certainly a consequence of the general trend towards lower antimony contents. Shorting through the separator is only found in cases of severe battery mistreatment. This positive, intermediary result is supplemented by an outlook on emerging development trends. Future automotive batteries will experience elevated operating temperatures, higher cycling loads, and maintenance freedom. Battery tests at temperatures up to 75 °C with various alloy combinations show that the hybrid design is best suited to meet the expected requirements. Microporous polyethylene pocket separation is not expected to be a limiting factor; the trend to lower antimony alloy content and increased cycling load will demonstrate the advantage of this separation even more clearly than in the past. Optimization of the already achieved, balanced separator characteristics profile with the reference parameters of electrical performance, water loss, durability and machinability will stimulate further development work.

Exploitation of a microporous organic polymer as a stationary phase for capillary gas chromatography

International Nuclear Information System (INIS)

Lu, Cuiming; Liu, Shuqin; Xu, Jianqiao; Ding, Yajuan; Ouyang, Gangfeng

2016-01-01

Microporous organic polymers (MOPs) have emerged as a new class of functional porous materials with unique characteristics and potential uses in diverse areas. However, the field of MOPs for gas chromatographic (GC) separations has not been well explored. Herein, a MOP namely KAPs-1 was dynamic coated onto a capillary column for the first time. The fabricated column exhibited a nonpolar nature and the column efficiency for n-dodecane was up to 7769 plates m"−"1. The KAPs-1 coated column showed high GC separation performance for a series of volatile organic compounds (VOCs) including the challenging ethylbenzene and xylene isomers, which could not be resolved at baseline on the commercial 5% phenyl polysiloxane stationary phase. Moreover, the relative standard deviations for five replicate determinations of the studied analytes were 0.0–0.6%, 0.9–3.2%, 1.1–5.9%, 0.8–3.7% for retention time, peak area, peak height and peak width, respectively. To investigate the interaction between some analytes and the stationary phase, thermodynamic and kinetic parameters were also evaluated. The results of this study show it is very promising to utilize MOPs as stationary phases for capillary GC. - Highlights: • A microporous organic polymer was explored as a novel stationary phase for capillary GC. • The column showed high separation performance for VOCs including the challenging ethylbenzene and xylene isomers. • Thermodynamic and kinetic parameters for BTEXs were determined to study the analyte-stationary phase interaction.

A novel TFC forward osmosis (FO) membrane supported by polyimide (PI) microporous nanofiber membrane

Science.gov (United States)

Chi, Xiang-Yu; Zhang, Ping-Yun; Guo, Xue-Jiao; Xu, Zhen-Liang

2018-01-01

A novel interfacial polymerization (IP) procedure on polyimide (PI) microporous nanofiber membrane support with mean pore size 1.27 μm was reported. Using m-phenylenediamine (MPD) as aqueous phase monomer, trimesoyl chloride (TMC) as organic phase monomer, ethanol as aqueous phase co-solvent, thin-film composite (TFC) forward osmosis (FO) membrane was fabricated by two IP procedures. The first IP procedure with the unconventional order (ie, the membrane was immersed in the TMC organic phase first, then in the co-solvent ethanol-water MPD aqueous phase) was used to diminish the pore size of PI microporous nanofiber membrane support for the formation of the polyamide layer. The secondary IP procedure was employed to form the relatively dense polyamide layer with conventional order (ie, the membrane was immersed in the co-solvent ethanol-water MPD aqueous phase first, then in the TMC organic phase). The experimental results showed that higher ethanol concentration led to the relatively higher pure water permeability in RO process and osmotic water flux in FO process, whereas NaCl rejection in RO process decreased and reverse salt flux increased. The specific salt flux (Js/Jv) of TFC FO PI nanofiber membrane (PIN-2-4) could be as low as 0.095 g/L in FO mode. These results could be attributed to influence of the addition of ethanol into aqueous phase on the surface morphology, hydrophilicity and polyamide layer structure.

Nanorod diameter modulated osteogenic activity of hierarchical micropore/nanorod-patterned coatings via a Wnt/β-catenin pathway.

Science.gov (United States)

Zhou, Jianhong; Zhao, Lingzhou; Li, Bo; Han, Yong

2018-04-14

Hierarchical micropore/nanorod-patterned strontium doped hydroxyapatite (Ca 9 Sr 1 (PO 4 ) 6 (OH) 2 , Sr 1 -HA) structures (MNRs) with different nanorod diameters of about 30, 70 and 150 nm were coated on titanium, to investigate the effect of nanorod diameter on osteogenesis and the involved mechanism. Compared to micropore/nanogranule-patterned Sr 1 -HA coating (MNG), MNRs gave rise to dramatically enhanced in vitro mesenchymal stem cell functions including osteogenic differentiation in the absence of osteogenic supplements and in vivo osseointegration related to the nanorod diameter with about 70 nm displaying the best effects. MNRs activated the cellular Wnt/β-catenin pathway by increasing the expression of Wnt3a and LRP6 and decreasing the expression of Wnt/β-catenin pathway antagonists (sFRP1, sFRP2, Dkk1 and Dkk2). The exogenous Wnt3a significantly enhanced the β-catenin signaling activation and cell differentiation on MNG, and the exogenous Dkk1 attenuated the enhancing effect of MNRs on them. The data demonstrate that MNRs favor osseointegration via a Wnt/β-catenin pathway. Copyright © 2018 Elsevier Inc. All rights reserved.

Electrochemically Produced Graphene for Microporous Layers in Fuel Cells.

Science.gov (United States)

Najafabadi, Amin Taheri; Leeuwner, Magrieta J; Wilkinson, David P; Gyenge, Előd L

2016-07-07

The microporous layer (MPL) is a key cathodic component in proton exchange membrane fuel cells owing to its beneficial influence on two-phase mass transfer. However, its performance is highly dependent on material properties such as morphology, porous structure, and electrical resistance. To improve water management and performance, electrochemically exfoliated graphene (EGN) microsheets are considered as an alternative to the conventional carbon black (CB) MPLs. The EGN-based MPLs decrease the kinetic overpotential and the Ohmic potential loss, whereas the addition of CB to form a composite EGN+CB MPL improves the mass-transport limiting current density drastically. This is reflected by increases of approximately 30 and 70 % in peak power densities at 100 % relative humidity (RH) compared with those for CB- and EGN-only MPLs, respectively. The composite EGN+CB MPL also retains the superior performance at a cathode RH of 20 %, whereas the CB MPL shows significant performance loss. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen adsorption on partially oxidised microporous carbons

International Nuclear Information System (INIS)

J B Parra; C O Ania; C J Duran Valle; M L Sanchez; C Otero Arean

2005-01-01

The search for cost effective adsorbents for large scale gas separation, storage and transport constitutes a present day strategic issue in the energy sector, propelled mainly by the potential use of hydrogen as an energy vector in a sustainable (and cleaner) energy scenario. Both, activated carbons and carbon based nano-structured materials have been proposed as potential candidates for reversible hydrogen storage in cryogenically cooled vessels. For that purpose, surface modification so as to enhance the gas solid interaction energy is desirable. We report on hydrogen adsorption on microporous (active) carbons which have been partially oxidised with nitric acid and ammonium persulfate. From the corresponding hydrogen adsorption isotherms (Fig. 1) an isosteric heat of about 3 kJ mol -1 was derived. This value is in agreement with that of about 3 to 4 kJ mol -1 obtained by quantum chemical calculations on the interaction between the hydrogen molecule and simple model systems (Fig. 2) of both, hydroxyl and carboxyl groups. Further research is in progress with a view to further increases the gas solid interaction energy. However, the values so far obtained are significantly larger than the liquefaction enthalpy of hydrogen: 0.90 kJ mol -1 ; and this is relevant to both, hydrogen separation from gas mixtures and cryogenic hydrogen storage. (authors)

Preparation of poly(acrylonitrile-butyl acrylate) gel electrolyte for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Tian Zheng [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); He Xiangming [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)]. E-mail: hexm@tsinghua.edu.cn; Pu Weihua [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Wan Chunrong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Jiang Changyin [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

2006-10-25

Poly(acrylonitrile-butyl acrylate) gel polymer electrolyte was prepared for lithium ion batteries. The preparation started with synthesis of poly(acrylonitrile-butyl acrylate) by radical emulsion polymerization, followed by phase inversion to produce microporous membrane. Then, the microporous gel polymer electrolytes (MGPEs) was prepared with the microporous membrane and LiPF{sub 6} in ethylene carbonate/diethyl carbonate. The dry microporous membrane showed a fracture strength as high as 18.98 MPa. As-prepared gel polymer electrolytes presented ionic conductivity in excess of 3.0 x 10{sup -3} S cm{sup -1} at ambient temperature and a decomposition voltage over 6.6 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for Li-ion batteries.

Mesoporous and microporous titania membranes

NARCIS (Netherlands)

Sekulic, J.

2004-01-01

The research described in this thesis deals with the synthesis and properties of ceramic oxide membrane materials. Since most of the currently available inorganic membranes with required separation properties have limited reliability and long-term stability, membranes made of new oxide materials

Compressive Deformation Behavior of Closed-Cell Micro-Pore Magnesium Composite Foam

Directory of Open Access Journals (Sweden)

Jing Wang

2018-05-01

Full Text Available The closed-cell micro-pore magnesium composite foam with hollow ceramic microspheres (CMs was fabricated by a modified melt foaming method. The effect of CMs on the compressive deformation behavior of CM-containing magnesium composite foam was investigated. Optical microscopy and scanning electron microscopy were used for observation of the microstructure. Finite element modeling of the magnesium composite foam was established to predict localized stress, fracture of CMs, and the compressive deformation behavior of the foam. The results showed that CMs and pores directly affected the compressive deformation behavior of the magnesium composite foam by sharing a part of load applied on the foam. Meanwhile, the presence of Mg2Si phase influenced the mechanical properties of the foam by acting as the crack source during the compression process.

Synthesis of hydroxyapatite with the use of calcium carbonate as of the biological precursor

International Nuclear Information System (INIS)

Aguilar, M.S.; Di Lello, B.C.; Queiroz, F.; Campos, N.C.; Campos, J.B.

2014-01-01

This work describes the synthesis of hydroxyapatite from calcium from biological materials such as shells carbonate. In the syntheses performed, the calcium carbonate of biological origin was used as the precursor and through a precipitation reaction with phosphoric acid, was converted into calcium hydroxide. Sequentially, the precipitate was aged, filtered, washed, dried and calcined, and then transformed into hydroxyapatite. The characterization of the powders was performed by X-DR (X-ray diffraction) and SEM (scanning electron microscopy). DR-X as determined hydroxyapatite calcium phosphate phase calcium. SEM revealed a morphology of finely divided particles. The method B.E.T. showed values of specific area and volume of micropores consistent with the literature. The results of the characterizations proved feasible to use for obtaining biological hydroxyapatite materials used in the reaction conditions.(author)

Microporous Cokes Formed in Zeolite Catalysts Enable Efficient Solar Evaporation

KAUST Repository

Wang, Jianjian

2017-03-13

Cokes are inevitably generated during zeolite-catalyzed reactions as deleterious side products that deactivate the catalyst. In this study, we in-situ converted cokes into carbons within the confined microporous zeolite structures and evaluated their performances as absorbing materials for solar-driven water evaporation. With a properly chosen zeolite, the cokederived carbons possessed ordered interconnected pores and tunable compositions. We found that the porous structure and the oxygen content in as-prepared carbons had important influences on their energy conversion efficiencies. Among various investigated carbon materials, the carbon derived from the methanol-to-olefins reaction over zeolite Beta gave the highest conversion efficiency of 72% under simulated sunlight with equivalent solar intensity of 2 suns. This study not only demonstrates the great potential of traditionally useless cokes for solar thermal applications but also provides new insights into the design of carbon-based absorbing materials for efficient solar evaporation.

Exploitation of a microporous organic polymer as a stationary phase for capillary gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Lu, Cuiming; Liu, Shuqin; Xu, Jianqiao; Ding, Yajuan; Ouyang, Gangfeng, E-mail: cesoygf@mail.sysu.edu.cn

2016-01-01

Microporous organic polymers (MOPs) have emerged as a new class of functional porous materials with unique characteristics and potential uses in diverse areas. However, the field of MOPs for gas chromatographic (GC) separations has not been well explored. Herein, a MOP namely KAPs-1 was dynamic coated onto a capillary column for the first time. The fabricated column exhibited a nonpolar nature and the column efficiency for n-dodecane was up to 7769 plates m{sup −1}. The KAPs-1 coated column showed high GC separation performance for a series of volatile organic compounds (VOCs) including the challenging ethylbenzene and xylene isomers, which could not be resolved at baseline on the commercial 5% phenyl polysiloxane stationary phase. Moreover, the relative standard deviations for five replicate determinations of the studied analytes were 0.0–0.6%, 0.9–3.2%, 1.1–5.9%, 0.8–3.7% for retention time, peak area, peak height and peak width, respectively. To investigate the interaction between some analytes and the stationary phase, thermodynamic and kinetic parameters were also evaluated. The results of this study show it is very promising to utilize MOPs as stationary phases for capillary GC. - Highlights: • A microporous organic polymer was explored as a novel stationary phase for capillary GC. • The column showed high separation performance for VOCs including the challenging ethylbenzene and xylene isomers. • Thermodynamic and kinetic parameters for BTEXs were determined to study the analyte-stationary phase interaction.

Effect of vacuum and of strong adsorbed water films on micropore formation in aluminum hydroxide xerogel powders.

Science.gov (United States)

Beruto, Dario T; Botter, Rodolfo; Converti, Attilio

2009-02-01

Aluminum hydroxide gels were washed with water, ethanol, methanol and isopropanol to obtain new gels with different liquid phases that were dried either in air at 120 degrees C or under vacuum at 80 degrees C. Drying in air leads to alcoholic xerogels with BET surface areas larger than the aqueous ones. The effect of the alcoholic groups as substitutes of the hydroxyl ones has been discussed to account for the final size of xerogel crystallites. Drying under vacuum decreases the BET surface of the methanol xerogels, but no micropores are formed in all the alcoholic xerogel matrixes. On the contrary, the vacuum drying process changes significantly the microstructure of the aqueous xerogels. Their BET surface increases by 34 m(2)/g, and micropores are formed within their crystallite aggregates. It has been experimentally shown that these changes are due to a shear transformation that occurs in the boehmite xerogels obtained under vacuum. To discuss these data, the existence of chemical compounds such as AlOOHnH(2)O was postulated. On this ground, a neat analogy between vacuum drying process and vacuum interfacial decomposition reactions of inorganic salts can be drawn. This analogy explains how a state of stresses forms in aqueous xerogel matrix during vacuum drying process.

Study on the Electrochemical Property of Microporous Cobalt Phosphite[Co_11(HPO_3)_8(OH)_6

International Nuclear Information System (INIS)

Lee, Dong Heon; Kang, Myunggoo; Jung, Hyun; Paek, Seung-Min

2016-01-01

Crystalline microporous cobalt phosphite, Co_11(HPO_3)_8(OH)_6, was prepared via facile hydrothermal route without the use of any templates or surfactants. The cobalt chloride hexahydrate (CoCl_2·6H_2O) and sodium hypophosphite monohydrate (NaH_2PO_2·H_2O) were employed as reactants, and sodium bicarbonate(NaHCO_3) was added to adjust the pH. The resultant Co_11(HPO_3)_8(OH)_6 shows dumbbell-like shape witha size of several micrometers. The obtained materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and energy dispersive spectrometry (EDS). The Co_11(HPO_3)_8(OH)_6 is applied as electrochemical energy storage electrode material because of its unique microporous nature. Different aqueous electrolytes (LiOH, NaOH, and KOH) have been tested in order to study the effect of electrolyte cations on electrochemical behavior. To investigate the capacity and stability of Co_11(HPO_3)_8(OH)_6 electrode, cyclic voltammetry (CV), galvanostatic charge-discharge (GC), and cycle stability were performed in aqueous electrolytes with different cations at room temperature. We found that the electrochemical behavior of these materials is strongly dependent on the species of electrolyte cations (Li"+,Na"+, and K"+).

High-performance carbon molecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide

KAUST Repository

Salinas, Octavio

2015-11-18

An intrinsically microporous polymer with hydroxyl functionalities, PIM-6FDA-OH, was used as a precursor for various types of carbon molecular sieve (CMS) membranes for ethylene/ethane separation. The pristine polyimide films were heated under controlled N2 atmosphere at different stages from 500 to 800 °C. All CMS samples carbonized above 600 °C surpassed the polymeric ethylene/ethane upper bound. Pure-gas selectivity reached 17.5 for the CMS carbonized at 800 °C with an ethylene permeability of about 10 Barrer at 2 bar and 35 °C, becoming the most selective CMS for ethylene/ethane separation reported to date. As expected, gravimetric sorption experiments showed that all CMS membranes had ethylene/ethane solubility selectivities close to one. The permselectivity increased with increasing pyrolysis temperature due to densification of the micropores in the CMS membranes, leading to enhanced diffusivity selectivity. Mixed-gas tests with a binary 50:50 v/v ethylene/ethane feed showed a decrease in selectivity from 14 to 8.3 as the total feed pressure was increased from 4 to 20 bar. The selectivity drop under mixed-gas conditions was attributed to non-ideal effects: (i) Competitive sorption that reduced the permeability of ethylene and (ii) dilation of the CMS that resulted in an increase in the ethane permeability.

Phase equilibrium and physical properties of biobased ionic liquid mixtures.

Science.gov (United States)

Toledo Hijo, Ariel A C; Maximo, Guilherme J; Cunha, Rosiane L; Fonseca, Felipe H S; Cardoso, Lisandro P; Pereira, Jorge F B; Costa, Mariana C; Batista, Eduardo A C; Meirelles, Antonio J A

2018-02-28

Protic ionic liquid crystals (PILCs) obtained from natural sources are promising compounds due to their peculiar properties and sustainable appeal. However, obtaining PILCs with higher thermal and mechanical stabilities for product and process design is in demand and studies on such approaches using this new IL generation are still scarce. In this context, this work discloses an alternative way for tuning the physicochemical properties of ILCs by mixing PILs. New binary mixtures of PILs derived from fatty acids and 2-hydroxy ethylamines have been synthesized here and investigated through the characterization of the solid-solid-[liquid crystal]-liquid thermodynamic equilibrium and their rheological and critical micellar concentration profiles. The mixtures presented a marked nonideal melting profile with the formation of solid solutions. This work revealed an improvement of the PILCs' properties based on a significant increase in the ILC temperature domain and the obtainment of more stable mesophases at high temperatures when compared to pure PILs. In addition, mixtures of PILs also showed significant changes in their non-Newtonian and viscosity profile up to 100 s -1 , as well as mechanical stability over a wide temperature range. The enhancement of the physicochemical properties of PILs here disclosed by such an approach leads to more new possibilities of their industrial application at high temperatures.

Synthesis of Zeolite Materials for Noble Gas Separation

International Nuclear Information System (INIS)

Achey, R.; Rivera, O.; Wellons, M.; Hunter, D.

2017-01-01

Microporous zeolite adsorbent materials are widely used as a medium for separating gases. Adsorbent gas separation systems can run at ambient temperature and require minimal pressure to flow the input gas stream across the adsorbent bed. This allows for low energy consumption relative to other types of separation systems. Specific zeolites also have a high capacity and selectivity for the gases of interest, leading to compact and efficient separation systems. These characteristics are particularly advantageous for the application of signatures detection for non-proliferation, which often requires portable systems with low power draw. Savannah River National Laboratory currently is the leader in using zeolites for noble gas sampling for non-proliferation detection platforms. However, there is a constant customer need for improved sampling capabilities. Development of improved zeolite materials will lead to improved sampling technology. Microwave-assisted and conventional hydrothermal synthesis have been used to make a variety of zeolites tailored for noble gas separation. Materials characterization data collected in this project has been used to help guide the synthesis of improved zeolite materials. Candidate materials have been down-selected based on highest available surface area, maximum overall capacity for gas adsorption and highest selectivity. The creation of improved adsorbent materials initiated in this project will lead to development of more compact, efficient and effective noble gas collectors and concentrators. The work performed in this project will be used as a foundation for funding proposals for further material development as well as possible industrial applications.

Synthesis of Zeolite Materials for Noble Gas Separation

Energy Technology Data Exchange (ETDEWEB)

Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rivera, O. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Wellons, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-02

Microporous zeolite adsorbent materials are widely used as a medium for separating gases. Adsorbent gas separation systems can run at ambient temperature and require minimal pressure to flow the input gas stream across the adsorbent bed. This allows for low energy consumption relative to other types of separation systems. Specific zeolites also have a high capacity and selectivity for the gases of interest, leading to compact and efficient separation systems. These characteristics are particularly advantageous for the application of signatures detection for non-proliferation, which often requires portable systems with low power draw. Savannah River National Laboratory currently is the leader in using zeolites for noble gas sampling for non-proliferation detection platforms. However, there is a constant customer need for improved sampling capabilities. Development of improved zeolite materials will lead to improved sampling technology. Microwave-assisted and conventional hydrothermal synthesis have been used to make a variety of zeolites tailored for noble gas separation. Materials characterization data collected in this project has been used to help guide the synthesis of improved zeolite materials. Candidate materials have been down-selected based on highest available surface area, maximum overall capacity for gas adsorption and highest selectivity. The creation of improved adsorbent materials initiated in this project will lead to development of more compact, efficient and effective noble gas collectors and concentrators. The work performed in this project will be used as a foundation for funding proposals for further material development as well as possible industrial applications.

Microporous Ni₁₁(HPO₃)₈(OH)₆ nanocrystals for high-performance flexible asymmetric all solid-state supercapacitors.

Science.gov (United States)

Gao, Yanping; Zhao, Junhong; Run, Zhen; Zhang, Guangqin; Pang, Huan

2014-12-07

Microporous nickel phosphite [Ni11(HPO3)8(OH)6] nanocrystals were prepared using a hydrothermal method, and were successfully applied as a positive electrode in a flexible all solid-state asymmetric supercapacitor. Because of the specific micro/nanostructure, the flexible solid-state asymmetric supercapacitor can achieve a maximum energy density of 0.45 mW h cm(-3), which is higher than most reported supercapacitors. More importantly, the device performance remains efficient for 10,000 cycles.

Influence of the electrolyte distribution near the micropores of the activated carbon (AC) electrode on high rate performance of high voltage capacitors

International Nuclear Information System (INIS)

Lee, Chung ho; Xu, Fan; Jung, Cheolsoo

2014-01-01

Highlights: • TFB can enhance the rate performance of high voltage capacitors. • TFB can suppress to increase the discharge slope to improve the cell performance. • TFB decreases the charge transfer resistance of an AC cell. • TFB affects the distribution of the electrolyte components near the microporous AC. - Abstract: This paper presents a method to enhance the rate performance of high voltage capacitors using an electrolyte additive, 1,3,5-trifluorobenzene (TFB). With increasing discharge rate, the capacity of the activated carbon (AC)/lithium (Li) cell decreases with increasing the slope of the discharge curve and its potential drop at 4.6 V. By adding TFB, the discharge slope improves to increase the rate performance of the cell, and EIS showed that the charge transfer resistance (Rc) of the AC cell decreases. These results suggest that TFB affects the distribution of the electrolyte components near the microporous AC and improves the rate performance of the AC cell

Numerical and experimental characterization of solid-state micropore-based cytometer for detection and enumeration of biological cells.

Science.gov (United States)

Guo, Jinhong; Chen, Liang; Ai, Ye; Cheng, Yuanbing; Li, Chang Ming; Kang, Yuejun; Wang, Zhiming

2015-03-01

Portable diagnostic devices have emerged as important tools in various biomedical applications since they can provide an effective solution for low-cost and rapid clinical diagnosis. In this paper, we present a micropore-based resistive cytometer for the detection and enumeration of biological cells. The proposed device was fabricated on a silicon wafer by a standard microelectromechanical system processing technology, which enables a mass production of the proposed chip. The working principle of this cytometer is based upon a bias potential modulated pulse, originating from the biological particle's physical blockage of the micropore. Polystyrene particles of different sizes (7, 10, and 16 μm) were used to test and calibrate the proposed device. A finite element simulation was developed to predict the bias potential modulated pulse (peak amplitude vs. pulse bandwidth), which can provide critical insight into the design of this microfluidic flow cytometer. Furthermore, HeLa cells (a type of tumor cell lines) spiked in a suspension of blood cells, including red blood cells and white blood cells, were used to assess the performance for detecting and counting tumor cells. The proposed microfluidic flow cytometer is able to provide a promising platform to address the current unmet need for point-of-care clinical diagnosis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Introduction to the first International Workshop on the Application of Microporous and Mesoporous Materials as Catalytic Hosts for Fe, Cu an Co

NARCIS (Netherlands)

Donk, van S.; Weckhuysen, B.M.; Kapteijn, F.; Kooyman, P.J.; Hensen, E.J.M.

2005-01-01

This Special Issue of Catalysis Today includes a selection of research presented at the first International Workshop on the ‘Application of Microporous and Mesoporous Materials as Catalytic Hosts for Fe, Cu and Co’, held in Scheveningen, The Netherlands, 1–4 March 2005. This 3-day event welcomed

A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2at room temperature

KAUST Repository

Li, Peng

2014-11-13

Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2at room temperature

KAUST Repository

Li, Peng; He, Yabing; Zhao, Yunfeng; Weng, Linhong; Wang, Hailong; Krishna, Rajamani A A; Wu, Hui; Zhou, Wei; O'Keeffe, Michael A.; Han, Yu; Chen, Banglin

2014-01-01

Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

FABRICATION OF MICROPOROUS SILICA CERAMICS WITH VARIED POLYMORPHIC FORMS AND INVESTIGATION OF THEIR THERMAL SHOCK BEHAVIOUR

Directory of Open Access Journals (Sweden)

Osman ŞAN

2011-06-01

Full Text Available In this study; the SiO₂ micro-porous ceramics in the phase α-quartz, α-cristobalite and β-cristobalite were produced and thermal shock resistance of products were compared. In the production of ceramic materials; α-quartz obtained from natural quartz powder, α-cristobalite from pure silica powder which prepared by Stöber technique and β-cristobalite from sol-gel approach. The β-composition was designed as Si₁₋⨯Al⨯Ca⨯/₂O₂ where x=0.05 and obtained gel was calcined at 850 °C. Before shaping, α-quartz powder and calcined β-cristobalite powder were grind in the planetary mill and the powder produced by Stöber technique was shaped directly without any milling process. The prepared powders were shaped by uniaxally press at 50 bars. The samples produced from α-quartz and β-cristobalite powders were sintered at 1150 °C and α-cristobalite obtained by Stöber technique was sintered at 1400 °C. In the defined polymorphic structure, micro-porous materials with pore size ~0.1-5 µm were produced and thermal shock tests were applied. Irrespective of β-cristobalite material, the samples were cracked and the tests could only repeat on the samples with β-cristobalite material. In the result, the β-cristobalite sample is believed to be great potential to use as a membrane filters for harsh thermal environments.

A microporous potassium vanadyl phosphate analogue of mahnertite. Hydrothermal synthesis and crystal structure

International Nuclear Information System (INIS)

Yakubovich, Olga V.; Russian Academy of Science, Moscow; Steele, Ian M.; Kiriukhina, Galina V.; Dimitrova, Olga V.

2015-01-01

The novel phase K 2.5 Cu 5 Cl(PO 4 ) 4 (OH) 0.5 (VO 2 ).H 2 O was prepared by hydrothermal synthesis at 553 K. Its crystal structure was determined using low-temperature (100 K) single-crystal synchrotron diffraction data and refined against F 2 to R = 0.035. The compound crystallizes in the tetragonal space group I4/mmm, with unit-cell parameters a =9.8120(8), c = 19.954(1) Aa, V = 1921.1(2) Aa 3 , and Z = 4. Both symmetrically independent Cu 2+ sites show elongated square-pyramidal coordination. The V 5+ ions reside in strongly distorted five-vertex VO 5 polyhedra with 50% occupancy. The structure is based on a 3D anionic framework built from Cu- and V-centered five-vertex polyhedra and PO 4 tetrahedra. Channels in the [100] and [010] directions accommodate large K atoms and H 2 O molecules. The compound is a new structural representative of the topology shown by the lavendulan group of copper arsenate and phosphate minerals. Their tetragonal or pseudotetragonal crystal structures are characterized by two types of 2D slabs alternating along one axis of their unit cells. One slab, described by the formula [Cu 4 X(TO 4 ) 4 ] 8 (where X = Cl, O and T = As, P), is common to all phases, whereas the slab content of the other set differs among the group members. We suggest interpreting this family of compounds in terms of the modular concept and also consider the synthetic phase Ba(VO)Cu 4 (PO 4 ) 4 as a simplest member of this polysomatic series.

Wettability control of micropore-array films by altering the surface nanostructures.

Science.gov (United States)

Chang, Chi-Jung; Hung, Shao-Tsu

2010-07-01

By controlling the surface nanostructure, the wettability of films with similar pore-array microstructure can be tuned from hydrophilic to nearly superhydrophobic without variation of the chemical composition. PA1 pore-array film consisting of the horizontal ZnO nanosheets was nearly superhydrophobic. PA2 pore-array film consisting of growth-hindered vertically-aligned ZnO nanorods was hydrophilic. The influences of the nanostructure shape, orientation and the micropore size on the contact angle of the PA1 films were studied. This study provides a new approach to control the wettability of films with similar pore-array structure at the micro-scale by changing their surface nanostructure. PA1 films exhibited irradiation induced reversible wettability transition. The feasibility of creating a wetted radial pattern by selective UV irradiation of PA1 film through a mask with radial pattern and water vapor condensation was also evaluated.

The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes

OpenAIRE

Akhmetshina, Alsu A.; Davletbaeva, Ilsiya M.; Grebenschikova, Ekaterina S.; Sazanova, Tatyana S.; Petukhov, Anton N.; Atlaskin, Artem A.; Razov, Evgeny N.; Zaripov, Ilnaz I.; Martins, Carla F.; Neves, Lu?sa A.; Vorotyntsev, Ilya V.

2015-01-01

Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested ...

Characterization of Coal Micro-Pore Structure and Simulation on the Seepage Rules of Low-Pressure Water Based on CT Scanning Data

Directory of Open Access Journals (Sweden)

Gang Zhou

2016-07-01

Full Text Available This paper used the X-ray three-dimensional (3D microscope and acquired, through CT scanning, the 3D data of the long-frame coal sample from the Daliuta Coal Mine. Then, the 3D datacube reconstructed from the coal’s CT scanning data was visualized with the use of Avizo, an advanced visualization software (FEI, Hillsboro, OR, USA. By means of a gray-scale segmentation technique, the model of the coal’s micro-pore structure was extracted from the object region, and the precise characterization was then conducted. Finally, the numerical simulation on the water seepage characteristics in the coal micro-pores model under the pressure of 3 MPa was performed on the CFX platform. Results show that the seepage of low-pressure water exhibited preference to the channels with large pore radii, short paths, and short distance from the outlet. The seepage pressure of low-pressure water decreased gradually along the seepage direction, while the seepage velocity of low-pressure water decreased gradually along the direction from the pore center to the wall. Regarding the single-channel seepage behaviors, the seepage velocity and mass flow rate of water seepage in the X direction were the largest, followed by the values of the seepage in the Y direction, and the seepage velocity and mass flow rate of water seepage in the Z direction were the smallest. Compared with the results in single-channel seepage, the dual-channel seepage in the direction of (X + Y and the multi-channel seepage in the direction of (X + Y + Z exhibited significant increases in the overall seepage velocity. The present study extends the application of 3D CT scanning data and provides a new idea and approach for exploring the seepage rules in coal micro-pore structures.

Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

KAUST Repository

Zhu, Haibo

2016-02-08

A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

KAUST Repository

Zhu, Haibo; Abou-Hamad, Edy; Chen, Yin; Saih, Youssef; Liu, Weibing; Basset, Jean-Marie; Samal, Akshaya Kumar

2016-01-01

A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

Microporous spongy chitosan monoliths doped with graphene oxide as highly effective adsorbent for methyl orange and copper nitrate (Cu(NO3)2) ions.

Science.gov (United States)

Wang, Ying; Liu, Xu; Wang, Hongfang; Xia, Guangmei; Huang, Wei; Song, Rui

2014-02-15

In the current study, microporous spongy chitosan monoliths doped with small amount of graphene oxide (CSGO monoliths) with high porosity (96-98%), extraordinary high water absorption (more than 2000%) and low density (0.0436-0.0607 g cm(-3)) were prepared by the freeze-drying method and used as adsorbents for anionic dyes methyl orange (MO) and Cu(2+) ions. The adsorption behavior of the CSGO monoliths and influencing factors such as pH value, graphene oxide (GO) content, concentration of pollutants as well as adsorption kinetics were studied. Specifically, the saturated adsorption capacity for MO is 567.07 mg g(-1), the highest comparing with other publication results, and it is 53.69 mg g(-1) for Cu(2+) ions. Since they are biodegradable, non-toxic, efficient, low-cost and easy to prepare, we believe that these microporous spongy CSGO monoliths will be the promising candidates for water purification. Copyright © 2013 Elsevier Inc. All rights reserved.

A microporous potassium vanadyl phosphate analogue of mahnertite. Hydrothermal synthesis and crystal structure

Energy Technology Data Exchange (ETDEWEB)

Yakubovich, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography; Russian Academy of Science, Moscow (Russian Federation). Inst. of Geology of Deposits, Petrography, Mineralogy and Geochemistry; Steele, Ian M. [Notre Dame Univ., IN (United States). Notre Dame Integrated Imaging Facility; Kiriukhina, Galina V.; Dimitrova, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography

2015-09-01

The novel phase K{sub 2.5}Cu{sub 5}Cl(PO{sub 4}){sub 4}(OH){sub 0.5}(VO{sub 2}).H{sub 2}O was prepared by hydrothermal synthesis at 553 K. Its crystal structure was determined using low-temperature (100 K) single-crystal synchrotron diffraction data and refined against F{sup 2} to R = 0.035. The compound crystallizes in the tetragonal space group I4/mmm, with unit-cell parameters a =9.8120(8), c = 19.954(1) Aa, V = 1921.1(2) Aa{sup 3}, and Z = 4. Both symmetrically independent Cu{sup 2+} sites show elongated square-pyramidal coordination. The V{sup 5+} ions reside in strongly distorted five-vertex VO{sub 5} polyhedra with 50% occupancy. The structure is based on a 3D anionic framework built from Cu- and V-centered five-vertex polyhedra and PO{sub 4} tetrahedra. Channels in the [100] and [010] directions accommodate large K atoms and H{sub 2}O molecules. The compound is a new structural representative of the topology shown by the lavendulan group of copper arsenate and phosphate minerals. Their tetragonal or pseudotetragonal crystal structures are characterized by two types of 2D slabs alternating along one axis of their unit cells. One slab, described by the formula [Cu{sub 4}X(TO{sub 4}){sub 4}]{sub 8} (where X = Cl, O and T = As, P), is common to all phases, whereas the slab content of the other set differs among the group members. We suggest interpreting this family of compounds in terms of the modular concept and also consider the synthetic phase Ba(VO)Cu{sub 4}(PO{sub 4}){sub 4} as a simplest member of this polysomatic series.

Light Hydrocarbons Adsorption Mechanisms in Two Calcium-based Microporous Metal Organic Frameworks

KAUST Repository

Plonka, Anna M.

2016-01-25

The adsorption mechanism of ethane, ethylene and acetylene (C2Hn; n=2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules trough C-H…π and C-H…O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations, with C2H6/CH4 selectivity as high as 74 in SBMOF-1.

Tunable CO 2 Adsorbents by Mixed-Linker Synthesis and Postsynthetic Modification of Zeolitic Imidazolate Frameworks

KAUST Repository

Thompson, Joshua A.; Brunelli, Nicholas A.; Lively, Ryan P.; Johnson, J. R.; Jones, Christopher W.; Nair, Sankar

2013-01-01

The incorporation of accessible amine functionality in zeolitic imidazolate frameworks (ZIFs) is used to improve the adsorption selectivity for CO 2/CH4 gas separation applications. Two synthetic approaches are described in this work to introduce functionality into the ZIF: (i) mixed-linker ZIF synthesis with 2-aminobenzimidazole as a substitution linker and (ii) postsynthetic modification of a mixed-linker ZIF with ethylenediamine. Using 2-aminobenzimidazole, a linker with a primary amine functional group, substitution of the ZIF-8 linker during synthesis allows for control over the adsorption properties while maintaining the ZIF-8 structure with up to nearly 50% substitution in the mixed-linker ZIF framework, producing a material with tunable pore size and amine functionality. Alternatively, postsynthetic modification of a mixed-linker ZIF containing an aldehyde functional group produces a ZIF material with a primary amine without detrimental loss of micropore volume by controlling the amount of functional group sites for modification. Both approaches using mixed-linker ZIFs yield new materials that show improvement in adsorption selectivity for the CO 2/CH4 gas pair over ZIF-8 and commercially available adsorbents as well as an increase in the heat of adsorption for CO2 without significant changes to the crystal structure. These results indicate that tuning the surface properties of ZIFs by either mixed-linker synthesis and/or postsynthetic modification may generate new materials with improved gas separation properties, thereby providing a new method for tailoring metal-organic frameworks. © 2013 American Chemical Society.

Tunable CO 2 Adsorbents by Mixed-Linker Synthesis and Postsynthetic Modification of Zeolitic Imidazolate Frameworks

KAUST Repository

Thompson, Joshua A.

2013-04-25

The incorporation of accessible amine functionality in zeolitic imidazolate frameworks (ZIFs) is used to improve the adsorption selectivity for CO 2/CH4 gas separation applications. Two synthetic approaches are described in this work to introduce functionality into the ZIF: (i) mixed-linker ZIF synthesis with 2-aminobenzimidazole as a substitution linker and (ii) postsynthetic modification of a mixed-linker ZIF with ethylenediamine. Using 2-aminobenzimidazole, a linker with a primary amine functional group, substitution of the ZIF-8 linker during synthesis allows for control over the adsorption properties while maintaining the ZIF-8 structure with up to nearly 50% substitution in the mixed-linker ZIF framework, producing a material with tunable pore size and amine functionality. Alternatively, postsynthetic modification of a mixed-linker ZIF containing an aldehyde functional group produces a ZIF material with a primary amine without detrimental loss of micropore volume by controlling the amount of functional group sites for modification. Both approaches using mixed-linker ZIFs yield new materials that show improvement in adsorption selectivity for the CO 2/CH4 gas pair over ZIF-8 and commercially available adsorbents as well as an increase in the heat of adsorption for CO2 without significant changes to the crystal structure. These results indicate that tuning the surface properties of ZIFs by either mixed-linker synthesis and/or postsynthetic modification may generate new materials with improved gas separation properties, thereby providing a new method for tailoring metal-organic frameworks. © 2013 American Chemical Society.

Formulation of stable Bacillus subtilis AH18 against temperature fluctuation with highly heat-resistant endospores and micropore inorganic carriers.

Science.gov (United States)

Chung, Soohee; Lim, Hyung Mi; Kim, Sang-Dal

2007-08-01

To survive the commercial market and to achieve the desired effect of beneficial organisms, the strains in microbial products must be cost-effectively formulated to remain dormant and hence survive through high and low temperatures of the environment during transportation and storage. Dormancy and stability of Bacillus subtilis AH18 was achieved by producing endospores with enhanced heat resistance and using inorganic carriers. Heat stability assays, at 90 degrees C for 1 h, showed that spores produced under a sublethal temperature of 57 degrees C was 100 times more heat-resistant than the ones produced by food depletion at the growing temperature of 37 degrees C. When these highly heat-resistant endospores were formulated with inorganic carriers of natural and synthetic zeolite or kaolin clay minerals having substantial amount of micropores, the dormancy of the endospores was maintained for 6 months at 15-25 degrees C. Meanwhile, macroporous perlite carriers with average pore diameter larger than 3.7 microm stimulated the germination of the spores and rapid proliferation of the bacteria. These results indicated that a B. subtilis AH18 product that can remain dormant and survive through environmental temperature fluctuation can be formulated by producing heat-stressed endospores and incorporating inorganic carriers with micropores in the formulation step.

Ultrathin Microporous SiO2 Membranes Photodeposited on Hydrogen Evolving Catalysts Enabling Overall Water Splitting

KAUST Repository

Bau, Jeremy A.; Takanabe, Kazuhiro

2017-01-01

Semiconductor systems for photocatalytic overall water splitting into H2 and O2 gases typically require metal cocatalyst particles, such as Pt, to efficiently catalyze H2 evolution. However, such metal catalyst surfaces also serve as recombination sites for H2 and O2, forming H2O. We herein report the photon-induced fabrication of microporous SiO2 membranes that can selectively restrict passage of O2 and larger hydrated ions while allowing penetration of protons, water, and H2. The SiO2 layers were selectively photodeposited on Pt nanoparticles on SrTiO3 photocatalyst by using tetramethylammonium (TMA) as a structure-directing agent (SDA), resulting in the formation of core–shell Pt@SiO2 cocatalysts. The resulting photocatalyst exhibited both improved overall water splitting performance under irradiation and with no H2/O2 recombination in the dark. The function of the SiO2 layers was investigated electrochemically by fabricating the SiO2 layers on a Pt electrode via an analogous cathodic deposition protocol. The uniform, dense, yet amorphous layers possess microporosity originating from ring structures formed during the hydrolysis of the silicate precursor in the presence of TMA, suggesting a double-role for TMA in coordinating silicate to cathodic surfaces and in creating a microporous material. The resulting layers were able to function as a molecular sieve, allowing for exclusive H2 generation while excluding unwanted side reactions by O2 or ferricyanide. The SiO2 layer is stable for extended periods of time in photocatalytic conditions, demonstrating promise as a nontoxic material for selective H2 evolution.

Ultrathin Microporous SiO2 Membranes Photodeposited on Hydrogen Evolving Catalysts Enabling Overall Water Splitting

KAUST Repository

Bau, Jeremy A.

2017-10-17

Semiconductor systems for photocatalytic overall water splitting into H2 and O2 gases typically require metal cocatalyst particles, such as Pt, to efficiently catalyze H2 evolution. However, such metal catalyst surfaces also serve as recombination sites for H2 and O2, forming H2O. We herein report the photon-induced fabrication of microporous SiO2 membranes that can selectively restrict passage of O2 and larger hydrated ions while allowing penetration of protons, water, and H2. The SiO2 layers were selectively photodeposited on Pt nanoparticles on SrTiO3 photocatalyst by using tetramethylammonium (TMA) as a structure-directing agent (SDA), resulting in the formation of core–shell Pt@SiO2 cocatalysts. The resulting photocatalyst exhibited both improved overall water splitting performance under irradiation and with no H2/O2 recombination in the dark. The function of the SiO2 layers was investigated electrochemically by fabricating the SiO2 layers on a Pt electrode via an analogous cathodic deposition protocol. The uniform, dense, yet amorphous layers possess microporosity originating from ring structures formed during the hydrolysis of the silicate precursor in the presence of TMA, suggesting a double-role for TMA in coordinating silicate to cathodic surfaces and in creating a microporous material. The resulting layers were able to function as a molecular sieve, allowing for exclusive H2 generation while excluding unwanted side reactions by O2 or ferricyanide. The SiO2 layer is stable for extended periods of time in photocatalytic conditions, demonstrating promise as a nontoxic material for selective H2 evolution.

Preparation And Characterization Of Microporous Activated Carbon From Oil Palm Shell By Physical Activation Using Purified Nitrogen

Directory of Open Access Journals (Sweden)

Allwar Allwar

2012-02-01

Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Oil palm shell, a byproduct of palm oil industry was successfully used as a raw material for the production of highly porous activated carbons. Preparation of activated carbon was carried out by physical activation under nitrogen at various activation temperatures. The nitrogen isotherms show Type I characteristics of microporous activated carbon. The maximum surface areas obtained at 900oC was 936 m2g-1. The morphology structure of the activated carbon indicated the existence of the porosities with different size pores. Keywords: Oil palm shell; Micropores; Physical activation; Nitrogen adsorption-desorption isotherm

Distribution of Interleukin-22-secreting Immune Cells in Conjunctival Associated Lymphoid Tissue.

Science.gov (United States)

Yoon, Chang Ho; Lee, Daeseung; Jeong, Hyun Jeong; Ryu, Jin Suk; Kim, Mee Kum

2018-04-01

Interleukin (IL)-22 is a cytokine involved in epithelial cell regeneration. Currently, no research studies have analyzed the distribution of the three distinct IL-22-secreting cell populations in human or mouse conjunctiva. This study investigated the distribution of the three main populations of IL-22-secreting immune cells, αβ Th cells, γδ T cells, or innate cells (innate lymphoid cells [ILCs] or natural killer cells), in conjunctival associated lymphoid tissues (CALTs) in human and mouse models. We collected discarded cadaveric bulbar conjunctival tissue specimens after preservation of the corneo-limbal tissue for keratoplasty from four enucleated eyes of the domestic donor. The bulbar conjunctiva tissue, including the cornea from normal (n = 27) or abraded (n = 4) B6 mice, were excised and pooled in RPMI 1640 media. After the lymphoid cells were gated in forward and side scattering, the αβ Th cells, γδ T cells, or innate lymphoid cells were positively or negatively gated using anti-CD3, anti-γδ TCR, and anti-IL-22 antibodies, with a FACSCanto flow cytometer. In normal human conjunctiva, the percentage and number of cells were highest in αβ Th cells, followed by γδ T cells and CD3- γδ TCR- IL-22+ innate cells (presumed ILCs, pILCs) (Kruskal-Wallis test, p = 0.012). In normal mice keratoconjunctiva, the percentage and total number were highest in γδ T cells, followed by αβ Th cells and pILCs (Kruskal-Wallis test, p = 0.0004); in corneal abraded mice, the population of αβ Th cells and pILCs tended to increase. This study suggests that three distinctive populations of IL-22-secreting immune cells are present in CALTs of both humans and mice, and the proportions of IL-22+αβ Th cells, γδ T cells, and pILCs in CALTs in humans might be differently distributed from those in normal mice. © 2018 The Korean Ophthalmological Society.

Microwave-Assisted Solvent-Free Synthesis of Zeolitic Imidazolate Framework-67

Directory of Open Access Journals (Sweden)

Heng Zhang

2016-01-01

Full Text Available A microporous metal-organic framework (MOF, cobalt-based zeolitic imidazolate framework-67 (ZIF-67, was synthesized by the combination of solvent-free hand-mill and microwave irradiation, without any organic solvent and within 30 minutes. The hand-milling process can mix the reactants well by the virtue of high moisture/water absorption capacity of reactants. In addition, the outstanding electromagnetic wave absorption capability of cobalt leads to efficient conversion to MOF structures before carbonization. The obtained ZIF-67 possesses high surface area and micropore volume.

Homo- and Copolycyclotrimerization of Aromatic Internal Diynes Catalyzed with Co-2(CO)(8): A Facile Route to Microporous Photoluminescent Polyphenylenes with Hyperbranched or Crosslinked Architecture

Czech Academy of Sciences Publication Activity Database

Sedláček, J.; Sokol, J.; Zedník, J.; Faukner, T.; Kubů, Martin; Brus, Jiří; Trhlíková, Olga

2018-01-01

Roč. 39, č. 4 (2018), č. článku 1700518. ISSN 1022-1336 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : microporous polymers * photoluminescence * polycyclotrimerization * polyphenylenes Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.265, year: 2016

Molecular Simulation of Adsorption in Microporous Materials

Directory of Open Access Journals (Sweden)

Yiannourakou M.

2013-11-01

Full Text Available The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications of Monte-Carlo simulation techniques, applied to the adsorption of fluids in microporous solids such as zeolites and model carbons (pores < 2 nm. Adsorption was computed in the Grand Canonical ensemble with the MedeA®-GIBBS software, using energy grids to decrease computing time. MedeA®-GIBBS has been used for simulations in the NVT or NPT ensembles to obtain the density and fugacities of fluid phases. Simulation results are compared with experimental pure component isotherms in zeolites (hydrocarbon gases, water, alkanes, aromatics, ethanethiol, etc., and mixtures (methane-ethane, n-hexane-benzene, over a large range of temperatures. Hexane/benzene selectivity inversions between silicalite and Na-faujasites are well predicted with published forcefields, providing an insight on the underlying mechanisms. Also, the adsorption isotherms in Na-faujasites for light gases or ethane-thiol are well described. Regarding organic adsorbents, models of mature kerogen or coal were built in agreement with known chemistry of these systems. Obtaining realistic kerogen densities with the simple relaxation approach considered here is encouraging for the investigation of other organic systems. Computing excess sorption curves in qualitative agreement with those recently measured on dry samples of gas shale is also favorable. Although still preliminary, such applications illustrate the strength of molecular modeling in understanding complex systems in conditions where experiments are difficult.

A multi-scaled hybrid orthopedic implant: bone ECM-shaped Sr-HA nanofibers on the microporous walls of a macroporous titanium scaffold.

Science.gov (United States)

Han, Yong; Zhou, Jianhong; Zhang, Lan; Xu, Kewei

2011-07-08

We report here, for the first time, a novel multi-scaled hybrid orthopedic implant material consisting of a macroporous Ti scaffold, whose macropores' walls have a microporous titania layer which is fully covered with nanofibers of Sr-doped hydroxyapatite (Sr-HA). The microporous titania layer is formed on and within the Ti scaffold by micro-arc oxidation, which firmly binds to the Ti substrate and contains Ca2+, Sr2+ and PO4(3-) ions. It is then hydrothermally treated to form Sr-HA nanofibers. During the hydrothermal treatment, Sr-HA nanoprisms nucleate from Ca0.5Sr0.5TiO3 pre-formed on the TiO2 and grow in length to nanofibers at the expense of Ca2+, Sr2+ and PO4(3-) ions that migrate from the TiO2. These Sr-HA nanofibers construct a network structure similar to the hierarchical organization of bone extracellular matrix (ECM), and the resulting nanofibrous surface displays a firm adhesion to substrate, superhydrophilicity and apatite-inducing ability. The induced apatite prefers to nucleate on the basal-faceted surfaces of Sr-HA nanofibers. The nanofiber-walled scaffold has a great potential for load-bearing orthotopic use.

In situ production of microporous foams in sub-millimeter cylindrical gold targets

International Nuclear Information System (INIS)

Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Yuan Guanghui; Wang Honglian; Zhou Lan; Zhang Lin; Du Kai

2009-01-01

The preparation of microcellular foam in sub-millimeter cylindrical gold targets is described. Small, open-ended, gold cylinders of 400 μm diameter, 700 μm length, and 20 μm wall thickness were fabricated by electroplating gold onto a silicon bronze mandrel and leaching the mandrel with concentrated nitric acid. After several rinsing and cleaning steps, the cylinders were filled with a solution containing acrylate monomers. The solution was polymerized in situ with ultraviolet light to produce a gel. Precipitation of these gels in a non-solvent such as methanol and subsequent drying by means of a critical point drying apparatus produced cylinders filled with microporous foams. The foams have densities of 50 mg · cm -3 and cell sizes on more than 1 μm. They fill the cylinders completely without shrinkage during the drying process, and need no subsequent machining. (authors)

Microporous Silico-Alumino Phosphate (SAPO) Compound For Uranium Sorption

International Nuclear Information System (INIS)

Siti-Amini

1998-01-01

The zeotype novel materials I.e. SAPO structures have been prepared to have particular property such as sorption or cations exchanger which can accommodate the uranyl ions. The SAPO's model was built from certain mole ratio of SiO 2 +AIO 2 +PO 2 using various template compounds of tetra(alkyl)s aminium hydroxide viz. Tetra-methyl, tetra-ethyl and tetra-propyl aminium. Those formed materials have been analyzed using x-ray diffraction spectrometer , then the data have been complied using the supporting software videozeo package Ver.3.1. The result have shown that crystalline structures of microporous SAPO materials formed are SAPO-20, SAPO-34, and SAPO-40. The exchanger capacities of some zeolites, SAPOs and ASP(1:3) have been studied and their selectivity to uranyl ions in acid solution (ph<3.5) has been determined by static isotherm exchanger process. The result have revealed various selectivity factors and occurrence of absorption mechanism in SAPO-n materials. This promises that uranium separation could be more effective using SAPO-n than that using other zeolites . The chloride ions have slightly decreased the ion-exchange capacity, while that of fluoride ions increased the ion-exchange capacity of ASP(1:3) for the uranyl ions

A combination of subcuticular suture and sterile Micropore tape compared with conventional interrupted sutures for skin closure. A controlled trial.

Science.gov (United States)

Taube, M.; Porter, R. J.; Lord, P. H.

1983-01-01

We have conducted a controlled trial to compare skin closure using conventional interrupted sutures with a combination of subcuticular suture and sterile Micropore tape in 169 patients undergoing appendicectomy, inguinal herniorrhaphy, or saphenofemoral ligation. We have found that the combination technique consistently gives a better cosmetic result and that the tape acts well as a dressing, is convenient, and is well tolerated by patients. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:6344732

A new addition to the Phillipsite family of molecular sieves: A divalent metal-ion-framework substituted microporous aluminophosphate (DAF-8)

Science.gov (United States)

Barrett, Philip A.; Sankar, Gopinathan; Stephenson, Richard; Catlow, C. Richard A.; Thomas, John Meurig; Jones, Richard H.; Teat, Simon J.

2006-03-01

By adding substantial amounts of either Co(II) or Zn(II) salts to a gel composed of Al 2O 3, P 2O 5 and the organic template 1,4-diaminocyclohexane, the tendency to yield layered aluminophosphates (AlPOs) is tilted in favour of the production of three-dimensional microporous MAlPOs: in particular, phase-pure samples of a novel Phillipsite structure (designated Davy-Faraday number 8, DAF-8) are formed.

Microporous uranyl chromates successively formed by evaporation from acidic solution

Energy Technology Data Exchange (ETDEWEB)

Siidra, Oleg I.; Nazarchuk, Evgeny V.; Bocharov, Sergey N.; Kayukov, Roman A. [St. Petersburg State Univ. (Russian Federation). Dept. of Crystallography; Depmeier, Wulf [Kiel Univ. (Germany). Inst. fuer Geowissenschaften

2018-04-01

The first microporous framework structures containing uranium and chromium have been synthesized and characterized. Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}](H{sub 2}O){sub 3} (1) was crystallized from uranyl chromate solution by evaporation. Further evaporation led to increased viscosity of the solution and overgrowing of Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O)](H{sub 2}O) (2) on the crystals of 1. With respect to 1, the framework of 2 is partially dehydrated. Both frameworks differ compositionally by only one water molecule, but this seemingly small difference affects significantly the pore size and overall structural topology of the frameworks, which present very different flexibility of the U-O-Cr links. These are rigid in the pillared framework of 1, in contrast to 2 where the U-O-Cr angles range from 126.3 to 168.2 , reflecting the substantial flexibility of Cr-O-U connections which make them comparable to the corresponding Mo-O-U links in uranyl molybdates.

Micropore Formation of [Zn2(Oxac) (Taz)2]·(H2O)2.5 via CO2 Adsorption.

Science.gov (United States)

Zubir, Moondra; Hamasaki, Atom; Iiyama, Taku; Ohta, Akira; Ohki, Hiroshi; Ozeki, Sumio

2017-01-24

As-synthesized [Zn 2 (Oxac) (Taz) 2 ]·(H 2 O) 2.5 , referred to as ZOTW 2.5 , was prepared from aqueous methanol solutions of Zn 5 (CO 3 ) 2 (OH) 6 and two kinds of ligands of 1,2,4-triazole (Taz) and oxalic acid (Oxac) at 453 K for 12 h. The crystal structure was determined by the Rietveld method. As-synthesized ZOTW 2.5 was pretreated at 383 K and 1 mPa for t pt h, ZOTW x (t pt h). ZOTW x (≥3h) showed a type I adsorption isotherm for N 2 at 77 K having a saturation amount (V s ) of 180 mg/g, but that pretreated shortly showed only 1/10 in V s . CO 2 was adsorbed at 303 K in sigmoid on nonporous ZOTW x (≤2h) and in Langmuir-type on ZOTW x (≥3h) to reach the adsorption amount of 120 mg/g at 700 Torr. N 2 adsorption on ZOTW x (≤2h)deCO 2 , degassed after CO 2 adsorption on ZOTW x (≤2h), was promoted 5-fold from 180 mg/g on ZOTW x (t pt h) and ZOTW x (≥3h)deCO 2 up to ca. 1000 mg/g. The interaction of CO 2 and H 2 O molecules in micropores may lead to a new route for micropore formation.

Super-microporous solid base MgO-ZrO2 composite and their application in biodiesel production

Science.gov (United States)

Su, Jiaojiao; Li, Yongfeng; Wang, Huigang; Yan, Xiaoliang; Pan, Dahai; Fan, Binbin; Li, Ruifeng

2016-10-01

The super-microporous microcrystalline MgO-ZrO2 nanomaterials (pore size 1-2 nm) was prepared successfully via a facile one-pot evaporation-induced self-assembly (EISA) method and employed in the transesterification of soybean oil and methanol. X-ray diffraction, transmission electron microscope, temperature programmed desorption of CO2, and N2 adsorption porosimetry were employed to characterize the nanocomposites. Nitrogen sorption isotherms revealed that these materials had large surface areas of more than 200 m2/g. Moreover, the sample with a Mg/Zr molar ratio of 0.5 and calcined at 400 °C showed high biodiesel yield (around 99% at 150 °C).

Direct synthesis of highly porous interconnected carbon nanosheets and their application as high-performance supercapacitors.

Science.gov (United States)

Sevilla, Marta; Fuertes, Antonio B

2014-05-27

An easy, one-step procedure is proposed for the synthesis of highly porous carbon nanosheets with an excellent performance as supercapacitor electrodes. The procedure is based on the carbonization of an organic salt, i.e., potassium citrate, at a temperature in the 750-900 °C range. In this way, carbon particles made up of interconnected carbon nanosheets with a thickness of <80 nm are obtained. The porosity of the carbon nanosheets consists essentially of micropores distributed in two pore systems of 0.7-0.85 nm and 0.95-1.6 nm. Importantly, the micropore sizes of both systems can be enlarged by simply increasing the carbonization temperature. Furthermore, the carbon nanosheets possess BET surface areas in the ∼1400-2200 m(2) g(-1) range and electronic conductivities in the range of 1.7-7.4 S cm(-1) (measured at 7.1 MPa). These materials behave as high-performance supercapacitor electrodes in organic electrolyte and exhibit an excellent power handling ability and a superb robustness over long-term cycling. Excellent results were obtained with the supercapacitor fabricated from the material synthesized at 850 °C in terms of both gravimetric and volumetric energy and power densities. This device was able to deliver ∼13 Wh kg(-1) (5.2 Wh L(-1)) at an extremely high power density of 78 kW kg(-1) (31 kW L(-1)) and ∼30 Wh kg(-1) (12 Wh L(-1)) at a power density of 13 kW kg(-1) (5.2 kW L(-1)) (voltage range of 2.7 V).

Bifunctionalized Intrinsically Microporous Polyimides with Simultaneously Enhanced Gas Permeability and Selectivity

KAUST Repository

Ma, Xiaohua; Mukaddam, Mohsin Ahmed; Pinnau, Ingo

2016-01-01

Two novel intrinsically microporous copolyimides synthesized by condensation reaction of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,3,3′,3′-tetramethyl-1,1′-spirobisindane-5,5′-diamino-6,6′-diol, and 3,5-diaminobenzoic acid with diamine ratios of 80/20 (Co-80/20) and 50/50 (Co-50/50) are reported. Unexpectedly, the Co-80/20 not only demonstrates higher microporosity (300 m2 g−1) than the PIM-6FDA-OH homopolymer (190 m2 g−1) but also exhibits simultaneously enhanced CO2 permeability (from 119 to 171 Barrer) and CO2/CH4 selectivity (from 35 to 41) after thermal annealing at 250 °C. This higher permeability originates from enhanced diffusivity (D CO2) and the higher selectivity results from its increased diffusion selectivity (D CO2/D CH4). After crosslinking at 300 °C, the Co-80/20 exhibits an even higher CO2 permeability (261 Barrer) and almost unchanged CO2/CH4 selectivity.

Bifunctionalized Intrinsically Microporous Polyimides with Simultaneously Enhanced Gas Permeability and Selectivity

KAUST Repository

Ma, Xiaohua

2016-03-29

Two novel intrinsically microporous copolyimides synthesized by condensation reaction of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,3,3′,3′-tetramethyl-1,1′-spirobisindane-5,5′-diamino-6,6′-diol, and 3,5-diaminobenzoic acid with diamine ratios of 80/20 (Co-80/20) and 50/50 (Co-50/50) are reported. Unexpectedly, the Co-80/20 not only demonstrates higher microporosity (300 m2 g−1) than the PIM-6FDA-OH homopolymer (190 m2 g−1) but also exhibits simultaneously enhanced CO2 permeability (from 119 to 171 Barrer) and CO2/CH4 selectivity (from 35 to 41) after thermal annealing at 250 °C. This higher permeability originates from enhanced diffusivity (D CO2) and the higher selectivity results from its increased diffusion selectivity (D CO2/D CH4). After crosslinking at 300 °C, the Co-80/20 exhibits an even higher CO2 permeability (261 Barrer) and almost unchanged CO2/CH4 selectivity.

Persistence of 1,2-dibromoethane in soils: entrapment in intraparticle micropores

International Nuclear Information System (INIS)

Steinberg, S.M.; Pignatello, J.J.; Sawhney, B.L.

1987-01-01

The soil fumigant 1,2-dibromoethane (EDB) was found in agricultural topsoils up to 19 years after its last known application. This residual EDB was highly resistant to both mobilization (desorption into air and water) and microbial degradation in contrast to freshly added EDB. Release of the residual EDB into aqueous solution was extremely slow at 25 0 C but highly temperature dependent. Treatment of release as a radial diffusion process yielded effective intraparticle diffusivities of (2-8) x 10 -7 cm 2 /s and half-equilibration times in a 1:2 soil-water suspension of 2-3 decades at 25 0 C. Aerobic degradation of residual EDB by indigenous microbes was negligible after 38 days compared to rapid removal and mineralization of added [ 14 C]EDB. The release of residual EDB was greatly enhanced by pulverization of the soil. The results show that the residual EDB is trapped in soil micropores other than the interlayers of expandable clays where release is influenced by extreme tortuosity or steric restriction. 27 references, 7 figures, 2 tables

Changes in optical properties, chemistry, and micropore and mesopore characteristics of bituminous coal at the contact with dikes in the Illinois Basin

Science.gov (United States)

Mastalerz, Maria; Drobniak, A.; Schimmelmann, A.

2009-01-01

Changes in high-volatile bituminous coal (Pennsylvanian) near contacts with two volcanic intrusions in Illinois were investigated with respect to optical properties, coal chemistry, and coal pore structure. Vitrinite reflectance (Ro) increases from 0.62% to 5.03% within a distance of 5.5??m from the larger dike, and from 0.63% to 3.71% within 3.3??m from the small dike. Elemental chemistry of the coal shows distinct reductions in hydrogen and nitrogen content close to the intrusions. No trend was observed for total sulfur content, but decreases in sulfate content towards the dikes indicate thermochemical sulfate reduction (TSR). Contact-metamorphism has a dramatic effect on coal porosity, and microporosity in particular. Around the large dike, the micropore volume, after a slight initial increase, progressively decreases from 0.0417??cm3/g in coal situated 4.7??m from the intrusive contact to 0.0126??cm3/g at the contact. Strongly decreasing mesopore and micropore volumes in the altered zone, together with frequent cleat and fracture filling by calcite, indicate deteriorating conditions for both coalbed gas sorption and gas transmissibility. ?? 2008 Elsevier B.V. All rights reserved.

Pleomorphic lobular carcinoma: is it more similar to a classic lobular cancer or to a high-grade ductal cancer?

Directory of Open Access Journals (Sweden)

Costarelli L

2017-12-01

Full Text Available Leopoldo Costarelli, Domenico Campagna, Alessandra Ascarelli, Francesco Cavaliere, Maria Helena Colavito, Tatiana Ponzani, Laura Broglia, Massimo La Pinta, Elena Manna, Lucio Fortunato Breast Unit, San Giovanni-Addolorata Hospital, Rome, Italy Background: Pleomorphic invasive lobular carcinoma (P-ILC is an uncommon variety of invasive lobular carcinoma with aggressive clinical features. Little is described in the literature regarding this topic.Materials and methods: We reviewed our experiences from 2010 to 2015 and compared 40 patients with P-ILC, 126 patients with classic-ILC (C-ILC and 574 cases of high-grade invasive ductal carcinoma (HG-IDC. We studied the histologic and immunohistochemical features, clinical presentation and surgical treatment.Results: P-ILC is diagnosed at the same age and tumor diameter as those of the other two histologic types. It is associated more frequently with multiple lymph node metastases and high proliferative index, and HER2/neu is amplified in 10% of cases. In spite of sharing some histologic characteristics with C-ILC (same growth pattern, loss of E-cadherin expression, same genetic pathway, its clinical and pathologic features define an autonomous entity. Its surgical treatment is similar to those of C-ILC and HG-IDC.Conclusion: This is the first review comparing these three pathologic entities. Our findings may be useful in understanding this variety of invasive lobular carcinoma, and further studies are certainly needed in this field. Keywords: breast cancer, lobular cancer, pleomorphic, mastectomy

Synthesis, characterization, and catalytic properties of stable mesoporous molecular sieve MCM-41 prepared from zeolite mordenite

International Nuclear Information System (INIS)

Wang Shan; Dou Tao; Li Yuping; Zhang Ying; Li Xiaofeng; Yan Zichun

2004-01-01

Mesoporous molecular sieves (denoted as M-MCM-41) with ordered hexagonal structure have been successfully synthesized from the assembly of precursors from preformed zeolite Mordenite with CTAB surfactant micelle in alkaline media. The samples were characterized by XRD, N 2 adsorption, IR and DTG. The materials exhibit highly hydrothermal stability, as compared with conventional MCM-41. Characterization results indicate that the mesoporous walls of M-MCM-41 contain the secondary building units similar to those in microporous crystal of zeolite Mordenite. In catalytic dealkylation of C10 + aromatic hydrocarbon, M-MCM-41 shows higher activities in comparison with Mordenite and MCM-41, which would be ascribed to the combination of advantages of both MCM-41 (large pores) and Mordenite (strong acidity). Furthermore, this synthesis strategy could be used as a new general method for the preparation of hydrothermally stable mesoporous aluminosilicate materials under alkaline conditions

Synthesis and characterization of α-alumina col-gel nanometric: elaboration of biomaterials nanostructured for biomedical applications

International Nuclear Information System (INIS)

Passoni, L.S.; Feit, G.; Camargo, N.H.A.

2010-01-01

The production of nanostructured biomaterials are research themes for these present new characteristics of biocompatibility and bioactivity. The sol-gel process allows obtaining α-alumina nanometric with purity 99.99%. The use of nanoparticles of Al 2 O 3 -α, SiO 2 and TiO 2 are being employed as a second stage in the development of nanocomposites biomaterials. The presence of the second phase within a ceramic matrix leads to obtaining nanomaterials with micropores in micro and nanostructures interconnected, what contributes within the processes of osseous integration, osseous induction. The goal of this work focused on synthesis and characterization of an α- alumina by sol-gel process. Characterization studies were conducted using the various techniques: X-ray diffraction, scanning electron microscopy, exploratory differential scanning calorimetry and infrared spectrometry by Fourier transforms. The preliminary results showed the attainment the nanometric α-alumina powder. (author)

Pili of oral Streptococcus sanguinis bind to fibronectin and contribute to cell adhesion.

Science.gov (United States)

Okahashi, Nobuo; Nakata, Masanobu; Sakurai, Atsuo; Terao, Yutaka; Hoshino, Tomonori; Yamaguchi, Masaya; Isoda, Ryutaro; Sumitomo, Tomoko; Nakano, Kazuhiko; Kawabata, Shigetada; Ooshima, Takashi

2010-01-08

Streptococcus sanguinis is a predominant bacterium in the human oral cavity and occasionally causes infective endocarditis. We identified a unique cell surface polymeric structure named pili in this species and investigated its functions in regard to its potential virulence. Pili of S. sanguinis strain SK36 were shown to be composed of three distinctive pilus proteins (PilA, PilB, and PilC), and a pili-deficient mutant demonstrated reduced bacterial adherence to HeLa and human oral epithelial cells. PilC showed a binding ability to fibronectin, suggesting that pili are involved in colonization by this species. In addition, ATCC10556, a standard S. sanguinis strain, was unable to produce pili due to defective pilus genes, which indicates a diversity of pilus expression among various S. sanguinis strains. Copyright 2009 Elsevier Inc. All rights reserved.

Synthesis of Porous Carbon Monoliths Using Hard Templates.

Science.gov (United States)

Klepel, Olaf; Danneberg, Nina; Dräger, Matti; Erlitz, Marcel; Taubert, Michael

2016-03-21

The preparation of porous carbon monoliths with a defined shape via template-assisted routes is reported. Monoliths made from porous concrete and zeolite were each used as the template. The porous concrete-derived carbon monoliths exhibited high gravimetric specific surface areas up to 2000 m²·g -1 . The pore system comprised macro-, meso-, and micropores. These pores were hierarchically arranged. The pore system was created by the complex interplay of the actions of both the template and the activating agent as well. On the other hand, zeolite-made template shapes allowed for the preparation of microporous carbon monoliths with a high volumetric specific surface area. This feature could be beneficial if carbon monoliths must be integrated into technical systems under space-limited conditions.

Silicon-Containing Tri- and Tetra-Functional Cyanate Esters: Synthesis, Cure Kinetics, and Network Properties

Science.gov (United States)

2014-01-01

organosilane monomers have also been described recently for use in the formation of microporous structures.15 Though the incorporation of silicon at...Song, J. K.; Alagar, M. Microporous Mesoporous Mater. 2013, 179, 157-164. 26. Wu, G. L.; Kou, K. C.; Chao, M.; Zhuo, L. H.; Zhang, J. Q. J. Wuhan Univ...Cambrea, L. R. Insights into moisture uptake and processability from new cyanate ester monomer and blend studies. SAMPE International Technical

A multi-scaled hybrid orthopedic implant: bone ECM-shaped Sr-HA nanofibers on the microporous walls of a macroporous titanium scaffold

Energy Technology Data Exchange (ETDEWEB)

Han Yong; Zhou Jianhong; Zhang Lan; Xu Kewei, E-mail: yonghan@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

2011-07-08

We report here, for the first time, a novel multi-scaled hybrid orthopedic implant material consisting of a macroporous Ti scaffold, whose macropores' walls have a microporous titania layer which is fully covered with nanofibers of Sr-doped hydroxyapatite (Sr-HA). The microporous titania layer is formed on and within the Ti scaffold by micro-arc oxidation, which firmly binds to the Ti substrate and contains Ca{sup 2+}, Sr{sup 2+} and PO{sub 4}{sup 3-} ions. It is then hydrothermally treated to form Sr-HA nanofibers. During the hydrothermal treatment, Sr-HA nanoprisms nucleate from Ca{sub 0.5}Sr{sub 0.5}TiO{sub 3} pre-formed on the TiO{sub 2} and grow in length to nanofibers at the expense of Ca{sup 2+}, Sr{sup 2+} and PO{sub 4}{sup 3-} ions that migrate from the TiO{sub 2}. These Sr-HA nanofibers construct a network structure similar to the hierarchical organization of bone extracellular matrix (ECM), and the resulting nanofibrous surface displays a firm adhesion to substrate, superhydrophilicity and apatite-inducing ability. The induced apatite prefers to nucleate on the basal-faceted surfaces of Sr-HA nanofibers. The nanofiber-walled scaffold has a great potential for load-bearing orthotopic use.

Combined Effect of a Microporous Layer and Type I Collagen Coating on a Biphasic Calcium Phosphate Scaffold for Bone Tissue Engineering

OpenAIRE

Mun-Hwan Lee; Changkook You; Kyo-Han Kim

2015-01-01

In this study, type I collagen was coated onto unmodified and modified microporous biphasic calcium phosphate (BCP) scaffolds. Surface characterization using a scanning electron microscope (SEM) and a surface goniometer confirmed the modification of the BCP coating. The quantity of the collagen coating was investigated using Sirius Red staining, and quantitative assessment of the collagen coating showed no significant differences between the two groups. MG63 cells were used to evaluate cell p...

A facile production of microporous carbon spheres and their electrochemical performance in EDLC

Science.gov (United States)

Xia, Xiaohong; Shi, Lei; Liu, Hongbo; Yang, Li; He, Yuede

2012-03-01

In the absence of activation process, we prepared a series of carbon particles from saccharine, in which hydrothermal carbonization method was used. These particles have spherical or near-spherical morphology, controllable monodisperse particle size from the analyses of SEM. Raman and XRD results show that they are nongraphitizable. The BET surface area of these carbon spherules is around 400-500 m2 g-1 and the microporosity is about 84%, suggesting that the carbon particles are rich in micropores. The electrochemical behaviors were characterized by means of galvanostatic charging/discharging, cycle voltammetry and impedance spectroscopy. The results show that the specific capacitance of sucrose-based carbon spherule reached 164 F g-1 in 30% KOH electrolyte and a high volumetric capacitance over 170 F cm-3 was obtained. These carbon spherules could be promising materials for EDLC according to their facile preparation way, low cost and high packing density.

Hybrid Materials for Molecular Sieves

NARCIS (Netherlands)

ten Elshof, Johan E.; Klein, Lisa; Aparicio, Mario; Jitianu, Andrei

2016-01-01

Hybrid microporous organosilica membranes for molecular separations made by acid-catalyzed solgel synthesis from bridged silsesquioxane precursors have demonstrated good performance in terms of flux and selectivity and remarkable hydrothermal stability in various pervaporation and gas separation

Electrochemical ion transfer across liquid/liquid interfaces confined within solid-state micropore arrays--simulations and experiments.

Science.gov (United States)

Strutwolf, Jörg; Scanlon, Micheál D; Arrigan, Damien W M

2009-01-01

Miniaturised liquid/liquid interfaces provide benefits for bioanalytical detection with electrochemical methods. In this work, microporous silicon membranes which can be used for interface miniaturisation were characterized by simulations and experiments. The microporous membranes possessed hexagonal arrays of pores with radii between 10 and 25 microm, a pore depth of 100 microm and pore centre-to-centre separations between 99 and 986 microm. Cyclic voltammetry was used to monitor ion transfer across arrays of micro-interfaces between two immiscible electrolyte solutions (microITIES) formed at these membranes, with the organic phase present as an organogel. The results were compared to computational simulations taking into account mass transport by diffusion and encompassing diffusion to recessed interfaces and overlapped diffusion zones. The simulation and experimental data were both consistent with the situation where the location of the liquid/liquid (l/l) interface was on the aqueous side of the silicon membrane and the pores were filled with the organic phase. While the current for the forward potential scan (transfer of the ion from the aqueous phase to the organic phase) was strongly dependent on the location of the l/l interface, the current peak during the reverse scan (transfer of the ion from the organic phase to the aqueous phase) was influenced by the ratio of the transferring ion's diffusion coefficients in both phases. The diffusion coefficient of the transferring ion in the gelified organic phase was ca. nine times smaller than in the aqueous phase. Asymmetric cyclic voltammogram shapes were caused by the combined effect of non-symmetrical diffusion (spherical and linear) and by the inequality of the diffusion coefficient in both phases. Overlapping diffusion zones were responsible for the observation of current peaks instead of steady-state currents during the forward scan. The characterisation of the diffusion behaviour is an important requirement

Carbon Molecular Sieve Membranes Derived from Tröger's Base-Based Microporous Polyimide for Gas Separation.

Science.gov (United States)

Wang, Zhenggong; Ren, Huiting; Zhang, Shenxiang; Zhang, Feng; Jin, Jian

2018-03-09

Carbon molecular sieve (CMS)-based membranes have attracted great attention because of their outstanding gas-separation performance. The polymer precursor is a key point for the preparation of high-performance CMS membranes. In this work, a microporous polyimide precursor containing a Tröger's base unit was used for the first time to prepare CMS membranes. By optimizing the pyrolysis procedure and the soaking temperature, three TB-CMS membranes were obtained. Gas-permeation tests revealed that the comprehensive gas-separation performance of the TB-CMS membranes was greatly enhanced relative to that of most state-of-the-art CMS membranes derived from polyimides reported so far. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic and Ionic Conductors from Ordered Microporous Materials

Energy Technology Data Exchange (ETDEWEB)

Dincă, Mircea [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2017-10-30

The proposed work aimed to establish metal-organic frameworks (MOFs) as new classes of high-surface area microporous electronic and ionic conductors. MOFs are crystalline materials with pore sizes ranging from 0.2 to ~ 2 nm (or larger for the latter) defined by inorganic or organic building blocks connected by rigid organic linkers. Myriad applications have been found or proposed for these materials, yet those that require electron transport or conductivity in combination with permanent porosity still lag behind because the vast majority of known frameworks are electrical insulators. Prior to our proposal and subsequent work, there were virtually no studies exploring the possibility of electronic delocalization in these materials. Therefore, our primary goal was to understand and control, at a fundamental level, the electron and ion transport properties of this class of materials, with no specific application proposed, although myriad applications could be envisioned for high surface area conductors. Our goals directly addressed one of the DOE-identified Grand Challenges for Basic Energy Sciences: designing perfect atom- and energy-efficient syntheses of revolutionary new forms of matter with tailored properties. Indeed, the proposed work is entirely synthetic in nature; owing to the molecular nature of the building blocks in MOFs, there is the possibility of unprecedented control over the structure and properties of solid crystalline matter. The goals also tangentially addressed the Grand Challenge of controlling materials processes at the level of electrons: the scope of our program is to create new materials where charges (electrons and/or ions) move according to predefined pathways.

Systematically controlled pore system of ordered mesoporous carbons using phosphoric acid as the in situ generated catalysts for carbonization and activation

Energy Technology Data Exchange (ETDEWEB)

Jin, Xing; Lee, Chang Hyun; Kim, Jin Hoe; You, Dae Jong; Shon, Jeong Kuk; Kim, Ji Man [Dept. of Chemistry, Sungkyunkwan University, Suwon (Korea, Republic of); Pak, Chan Ho [Fuel Cell Group, Corporate R and D Center, Samsung SDI Co. Ltd., Yongin (Korea, Republic of)

2015-08-15

We report on a facile synthesis of the ordered mesoporous carbon (OMC) materials with systematically controlled microporosity and mesoporosity simultaneously through the nano-replication route using phosphoric acid as the acid catalyst and activation agent. The use of phosphoric acid affects the pore structures of OMC materials, such as the formation of numerous micropores by activation of the carbon framework and the enlargement of mesopores by spontaneous phase separation during the carbonization. The mesopore sizes, surface areas, total pore volumes, and micropore volumes of the OMC materials are highly dependent on the phosphoric acid content and can be systematically controlled in the range 3.7–7.5 nm, 1027–2782 m{sup 2} g{sup -1}, 1.12–3.53 cm{sup 3} g{sup -1} and 0.34–0.95 cm{sup 3} g{sup -1}, respectively. OMC materials with systematically controlled pore structures were successfully synthesized using phosphoric acid as the carbonization catalyst and mesoporous silica materials with cubic Ia3d and 2-D hexagonal mesostructures as the templates. The phosphoric acid in the synthesis of ordered mesoporous carbon materials acts as the chemical activating agent for micropore generation of the carbon framework and pore-expanding agent for controlling of mesopore size, in addition to functioning as the acid catalyst. The present synthesis pathway is very useful for preparing OMC materials with tunable mesopore sizes and well-developed microporosities at the same time.

用于空气中水蒸气吸-脱附的微孔泡沫炭制备研究%Preparation of microporous carbon foams for adsorption/desorption of water vapor in ambient air

Institute of Scientific and Technical Information of China (English)

Naoto Ohta; Yoko Nishi; Takahiro Morishita; Yumiko Ieko; Akifumi Ito; Michio Inagaki

2008-01-01

以蜜胺泡沫体为模板,采用氟化聚酰业胺制备了微孔泡沫炭.测定了其对环境中水气的吸附/脱附行为,发现:泡沫炭在空气中400℃活化1 h,可以提高其对水气的吸附能力.与活化前相比,对水气的吸附量几乎高达3倍,尽管其微孔容积仅增大了1.5倍.对环境水气中的可逆吸附率与微孔容积成线性关系,微孔容积为0.75mL/g的泡沫炭,其水气吸附率约为质最分数40%.%Microporous carbon foams were prepared from a fluorinated polyimide using melamine foam as a template. The adsorption/desorption behavior of water vapor in ambient air was examined. The activation of carbon foams at 400℃ for 1 h in air was found to be effective in increasing the adsorptivity of water vapor. The amount of water vapor adsorbed after air activation was almost 3 times as large as that before activation, although the micropore volume increase was only 1.5 times. The reversible adsorptivity for water vapor in ambient air showed a linear dependence on micropore volume with an adsorptivity of about 40% mass fraction for a micropore volume of 0.75 mL/g.

New Microporous Polymer Electrolyte Based on Polysiloxane Grafted with Imidazolium Iodide Moieties for DSSC

Directory of Open Access Journals (Sweden)

Yan Yang

2011-01-01

Full Text Available Two types of polysiloxane grafted with different ratio of imidazolium iodide moieties (IL-SiO2 have been synthesized to develop a micro-porous polymer electrolyte for quasi-solid-state dye-sensitized solar cells. The samples were characterized by 1HNMR, FT-IR spectrum, XRD, TEM and SEM, respectively. Moreover, the ionic conductivity of the electrolytes was measured by electrochemical workstation. Nanostructured polysiloxane containing imidazolium iodide showed excellent compatibility with organic solvent and polymer matrix for its ionic liquid characteristics. Increasing the proportion of imidazolium iodide moieties in polysiloxane improved the electrochemical behavior of the gel polymer electrolyte. A dye-sensitized solar cell with gel polymer electrolyte yielded an open-circuit voltage of 0.70 V, short-circuit current of 11.19 mA cm−2, and the conversion efficiency of 3.61% at 1 sun illumination.

Epitaxially Grown Layered MFI–Bulk MFI Hybrid Zeolitic Materials

KAUST Repository

Kim, Wun-gwi; Zhang, Xueyi; Lee, Jong Suk; Tsapatsis, Michael; Nair, Sankar

2012-01-01

The synthesis of hybrid zeolitic materials with complex micropore-mesopore structures and morphologies is an expanding area of recent interest for a number of applications. Here we report a new type of hybrid zeolite material, composed of a layered

Facile Synthesis of Yolk/Core-Shell Structured TS-1@Mesosilica Composites for Enhanced Hydroxylation of Phenol

KAUST Repository

Zou, Houbing

2015-12-14

© 2015 by the authors. In the current work, we developed a facile synthesis of yolk/core-shell structured TS-1@mesosilica composites and studied their catalytic performances in the hydroxylation of phenol with H2O2 as the oxidant. The core-shell TS-1@mesosilica composites were prepared via a uniform coating process, while the yolk-shell TS-1@mesosilica composite was prepared using a resorcinol-formaldehyde resin (RF) middle-layer as the sacrificial template. The obtained materials were characterized by X-ray diffraction (XRD), N2 sorption, Fourier transform infrared spectoscopy (FT-IR) UV-Visible spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characterization results showed that these samples possessed highly uniform yolk/core-shell structures, high surface area (560–700 m2 g−1) and hierarchical pore structures from oriented mesochannels to zeolite micropores. Importantly, owing to their unique structural properties, these composites exhibited enhanced activity, and also selectivity in the phenol hydroxylation reaction.

[Study on the interface of human hepatocyte/micropore polypropylene ultrafiltration membrane].

Science.gov (United States)

Peng, Cheng-Hong; Han, Bao-San; Gao, Chang-You; Ma, Zu-Wei; Zhao, Zhi-Ming; Wang, Yong; Liu, Hong; Zhang, Gui-di; Yang, Mei-Juan

2004-09-02

To found a new interface of human hepatocyte/micropore polypropylene ultrafiltration membrane (MPP) with good cytocompatibility so as to construct bioartificial bioreactor with polypropylene hollow fibers in future. MPP ultrafiltration membrane underwent chemical grafting modification through ultraviolet irradiation and Fe(2+) reduction. The contact angles of MPP and the modified MPP membranes were measured. Human hepatic cells L-02 were cultured. MPP and modified MPP membranes were spread on the wells of culture plate and human hepatic cells and cytodex 3 were inoculated on them. Different kinds of microscopy were used to observe the morphology of these cells. The water contact angle of MPP and the modified MPP membranes decreased from 78 degrees +/- 5 degrees to 27 degrees +/- 4 degrees (P < 0.05), which indicated that the hydrophilicity of the membrane was improved obviously after the grafting modification. Human hepatocyte L-02 did not adhere to and spread on the modified MPP membrane surface, and only grew on the microcarrier cytodex 3 with higher density and higher proliferation ratio measured by MTT. Grafting modification of acrylamide on MPP membrane is a good method to improve the human hepatocyte cytocompatibility with MPP ultrafiltration membrane.

Binary gas mixture adsorption-induced deformation of microporous carbons by Monte Carlo simulation.

Science.gov (United States)

Cornette, Valeria; de Oliveira, J C Alexandre; Yelpo, Víctor; Azevedo, Diana; López, Raúl H

2018-07-15

Considering the thermodynamic grand potential for more than one adsorbate in an isothermal system, we generalize the model of adsorption-induced deformation of microporous carbons developed by Kowalczyk et al. [1]. We report a comprehensive study of the effects of adsorption-induced deformation of carbonaceous amorphous porous materials due to adsorption of carbon dioxide, methane and their mixtures. The adsorption process is simulated by using the Grand Canonical Monte Carlo (GCMC) method and the calculations are then used to analyze experimental isotherms for the pure gases and mixtures with different molar fraction in the gas phase. The pore size distribution determined from an experimental isotherm is used for predicting the adsorption-induced deformation of both pure gases and their mixtures. The volumetric strain (ε) predictions from the GCMC method are compared against relevant experiments with good agreement found in the cases of pure gases. Copyright © 2018 Elsevier Inc. All rights reserved.

Flute type micropores activated carbon from cotton stalk for high performance supercapacitors

Science.gov (United States)

Tian, Xun; Ma, Hongru; Li, Zhe; Yan, Shaocun; Ma, Lei; Yu, Feng; Wang, Gang; Guo, Xuhong; Ma, Yanqing; Wong, Chingping

2017-08-01

Flute type micropores activated carbon (FTMAC) has been successfully obtained from cotton stalk via KOH-chemical activation method. The synthesized carbon material exhibits an ordered pore structure with high specific surface area of 1964.46 m2 g-1 and pore volume of 1.03 m3 g-1. The assembled FTMAC-based electrode delivers a high specific capacitance of 254 F g-1 at a current density of 0.2 A g-1 in 1 M H2SO4 aqueous electrolyte. It still can maintain 221 F g-1at a current density of 10 A g-1, demonstrating a good rate capacity (87% retention), as well as long cyclic stability of 96% capacitance retention after 10000 charging and discharging cycles at current density of 1 A g-1. Moreover, the symmetric supercapacitor can deliver a high energy density of 18.14 W h kg-1 and a power density of 450.37 W kg-1 which is operated in the voltage range of 0-1.8 V.

Numerical analysis of a red blood cell flowing through a thin micropore.

Science.gov (United States)

Omori, Toshihiro; Hosaka, Haruki; Imai, Yohsuke; Yamaguchi, Takami; Ishikawa, Takuji

2014-01-01

Red blood cell (RBC) deformability plays a key role in microcirculation, especially in vessels that have diameters even smaller than the nominal cell size. In this study, we numerically investigate the dynamics of an RBC in a thin micropore. The RBC is modeled as a capsule with a thin hyperelastic membrane. In a numerical simulation, we employ a boundary element method for fluid mechanics and a finite element method for membrane mechanics. The resulting RBC deformation towards the flow direction is suppressed considerably by increased cytoplasm viscosity, whereas the gap between the cell membrane and solid wall becomes smaller with higher cytoplasm viscosity. We also measure the transit time of the RBC and find that nondimensional transit time increases nonlinearly with respect to the viscosity ratio, whereas it is invariant to the capillary number. In conclusion, cytoplasmic viscosity plays a key role in the dynamics of an RBC in a thin pore. The results of this study will be useful for designing a microfluidic device to measure cytoplasmic viscosity.

Enhanced adsorption of benzene vapor on granular activated carbon under humid conditions due to shifts in hydrophobicity and total micropore volume.

Science.gov (United States)

Liu, Han-Bing; Yang, Bing; Xue, Nan-Dong

2016-11-15

A series of hydrophobic-modified (polydimethylsiloxane (PDMS) coating) activated carbons (ACs) were developed to answer a fundamental question: what are the determinants that dominate the adsorption on ACs under humid conditions? Using column experiments, an inter-comparison among bare-AC and PDMS-coated ACs was conducted regarding the association of surface characteristics and adsorption capacity. Primary outcomes occurred in two dominating markers, hydrophobicity and total micropore volume, which played a key role in water adsorption on ACs. However, their contributions to water adsorption on ACs substantially differed under different Pwater/Pair conditions. Hydrophobicity was the only contributor in Pwater/Pair=0.1-0.6, while the two markers contributed equally in Pwater/Pair=0.7-1.0. Furthermore, PDMS-coated AC had a significant increase in benzene adsorption capacities compared to bare-AC at 0-90% relative humidity, while these differences were not significant among PDMS-coated ACs. It is thus presumed that the balance between the two markers can be shifted to favor almost unchanged benzene adsorption capacities among PDMS-coated ACs over a large range of relative humidity. These findings suggest potential benefits of PDMS coating onto ACs in enhancing selective adsorption of hydrophobic volatile organic compounds under high humid conditions. To develop new porous materials with both high total micropore volume and hydrophobicity should thus be considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Separation of carbon dioxide from flue gas by mixed matrix membranes using dual phase microporous polymeric constituents.

Science.gov (United States)

Sekizkardes, Ali K; Kusuma, Victor A; Dahe, Ganpat; Roth, Elliot A; Hill, Lawrence J; Marti, Anne; Macala, Megan; Venna, Surendar R; Hopkinson, David

2016-09-27

This study presents the fabrication of a new mixed matrix membrane using two microporous polymers: a polymer of intrinsic microporosity PIM-1 and a benzimidazole linked polymer, BILP-101, and their CO 2 separation properties from post-combustion flue gas. 17, 30 and 40 wt% loadings of BILP-101 into PIM-1 were tested, resulting in mechanically stable films showing very good interfacial interaction due to the inherent H-bonding capability of the constituent materials. Gas transport studies showed that BILP-101/PIM-1 membranes exhibit high CO 2 permeability (7200 Barrer) and selectivity over N 2 (15). The selected hybrid membrane was further tested for CO 2 separation using actual flue gas from a coal-fired power plant.

Tailoring the porosity of hierarchical zeolites by carbon-templating

DEFF Research Database (Denmark)

Zhu, Kake; Egeblad, Kresten; Christensen, Claus H.

2008-01-01

We report the synthesis and characterization of a series of hierarchical porous zeolite single crystal materials with a range of porosities made available by carbon-templating using differently-sized carbon particles as templates for the additional non-micropore porosity. The materials were...

Enhanced catalytic oxidation by hierarchically structured TS-1 zeolite

NARCIS (Netherlands)

Xin, H.; Zhao, Jiao; Zhao, J.; Xu, S.; Li, Junping; Zhang, Weiping; Guo, X.; Hensen, E.J.M.; Yang, Q.; Li, Can

2010-01-01

A TS-1 zeolite with a disordered network of mesopores penetrating the microporous crystalline zeolite framework was successfully synthesized by a one-pot carbon hard-templating synthesis approach. Besides conventional methods to characterize the mesoporosity, the use of variable-temperature 129Xe

Application of water-soluble polyvinyl alcohol-based film patches on laser microporated skin facilitates intradermal macromolecule and nanoparticle delivery.

Science.gov (United States)

Engelke, Laura; Winter, Gerhard; Engert, Julia

2018-07-01

The intradermal delivery of biologics has long been recognized as attractive approach for cutaneous immunotherapy, particularly vaccination. Although intradermal (i.d.) or subcutaneous (s.c.) injection provide reproducible dosing and good cost- and delivery efficiency, the major objective to avoid sharps and the need for enhanced storage stability have renewed the interest in alternative needle-free delivery strategies. This study presents a new concept for the delivery of macromolecules and nanoparticles to viable skin layers with a high density of professional antigen-presenting cells (APCs). Stable polyvinyl alcohol (PVA) polymer films as well as PVA blends with carboxymethyl cellulose (CMC) or cross-linked carbomer were prepared using an easily-scalable film casting technique. Fluorescein isothiocyanate (FITC) and rhodamine B-labeled dextrane 70 kDa (RD70), used as small and macromolecular model substances, or polystyrene (PS)-nano- and microparticles with diameters of 0.5 µm and 5 µm were directly incorporated into the polymer formulations at varying concentrations. The assembly of the polymer films with an occlusive backing tape created a film patch that provided a fast drug release upon dissolution of the water-soluble film and facilitated an intradermal drug delivery on laser microporated skin. The minimally-invasive P.L.E.A.S.E.® laser poration system (Pantec Biosolutions, Ruggell, Liechtenstein) provided access to viable skin layers by thermally ablating the superficial tissue with a pulsed Er:YAG laser (λ = 2.94 µm). In our in vitro study using excised pig skin, laser microporation induced a 4- to 5-fold increase of water transport (TEWL) through excised skin in a Franz diffusion cell compared to intact skin. The TEWL values detected were comparable to in vivo human skin. The increased water transport facilitated the dissolution of all topically applied dry PVA-based film formulations within 6 h. No dissolution of the films was seen on

Release Kinetics and Antibacterial Efficacy of Microporous β-TCP Coatings

Directory of Open Access Journals (Sweden)

Michael Seidenstuecker

2013-01-01

Full Text Available Purpose. The aim of this study was to impregnate microporous β-TCP scaffolds with different antibiotic solutions and to determine their release behavior. Materials and Methods. We impregnated a β-TCP scaffold with antibiotics by using three methods: drop, dip, and stream coating with 120 mg/mL of antibiotic solution. After drying for 72 h at 37°C, 2 mL of distilled water was added to the antibiotic-coated plugs and incubated at 37°C. After defined time points (1, 2, 3, 6, 9, and 14 days, the liquid was completely replaced. The extracted liquid was analyzed by capillary zone electrophoresis and the Kirby Bauer disc diffusion test. For statistical analysis, we calculated a mean and standard deviation and carried out an analysis of variance using ANOVA. Results. The VAN and CLI release from the β-TCP scaffolds was rapid, occurring within 24 h with 89 ± 0.8% VAN and 90.4 ± 1.5% CLI regardless of the type of insulation. After six days, the VAN and CLI were completely released. All samples taken at later time points had a VAN or CLI concentration below the detection limit of 4 µg/mL. The released amounts of VAN and CLI within the first three days revealed antimicrobial activity.

Non-linear frequency response of non-isothermal adsorption controlled by micropore diffusion with variable diffusivity

Directory of Open Access Journals (Sweden)

MENKA PETKOVSKA

2000-12-01

Full Text Available The concept of higher order frequency response functions (FRFs is used for the analysis of non-linear adsorption kinetics on a particle scale, for the case of non-isothermal micropore diffusion with variable diffusivity. Six series of FRFs are defined for the general non-isothermal case. A non-linerar mathematical model is postulated and the first and second order FRFs derived and simulated. A variable diffusivity influences the shapes of the second order FRFs relating the sorbate concentration in the solid phase and t he gas pressure significantly, but they still keep their characteristics which can be used for discrimination of this from other kinetic mechanisms. It is also shown that first and second order particle FRFs offter sufficient information for an easy and fast estimation of all model parameters, including those defining the system non-linearity.

Carbonization-dependent nitrogen-doped hollow porous carbon nanospheres synthesis and electrochemical study for supercapacitors

Science.gov (United States)

Zhou, Lingyun; Xie, Guohong; Chen, Xiling

2018-05-01

In this paper, a nitrogen-doped hollow microporous carbon nanospheres was synthesized via the combination of hyper-crosslinking mediated self-assembly and further pyrolysis using polylactide-b-polystyrene (PLA-b-PS) copolymers and aniline monomers as precursor. The pore structure and the correlative electrochemical performance of nitrogen-doped hollow microporous carbon nanospheres were affected by the molar mass ratio of aniline and PS in block copolymers and the carbonization conditions. The electrochemical measurements results showed that the obtained PLA150-PS250-N4-900-10H sample with nitrogen content of 3.57% and the BET surface area of 945 m2 g-1 displays the best capacitance performance. At a current density of 1.0 Ag-1, the resultant specific capacitance is 250 Fg-1. In addition, it also exhibits high capacitance retention of 98% after charging-discharging 1500 times at 25 Ag-1. The results demonstrate the nitrogen-doped hollow microporous carbon nanospheres can be used as promising supercapacitor electrode materials for high performance energy storage devices.

Towards chiral distributions of dopants in microporous frameworks: helicoidal supramolecular arrangement of (1R,2S)-ephedrine and transfer of chirality.

Science.gov (United States)

Gómez-Hortigüela, Luis; Álvaro-Muñoz, Teresa; Bernardo-Maestro, Beatriz; Pérez-Pariente, Joaquín

2015-01-07

A molecular-mechanics computational study is performed in order to analyze the arrangement of (1R,2S)-(-)-ephedrine molecules within the 12-MR channels of the AFI aluminophosphate microporous framework and the influence on the spatial distribution of dopants embedded in the tetrahedral network. Results showed that ephedrine molecules arrange exclusively as dimers by π-π stacking of the aromatic rings within the AFI channels. Interestingly, the asymmetric nature of ephedrine and the presence of H-bond-forming groups (NH2 and OH) involve a preferential orientation where consecutive dimers within the channels are rotated by an angle of +30°; this is driven by the establishment of inter-dimer H-bonds. This preferential orientation leads to the development of a supramolecular enantiomerically-pure helicoidal (chiral) arrangement of ephedrine dimers. In addition, the computational results demonstrate that the particular molecular structure of ephedrine imparts a strong trend to attract negative charges to the vicinity of the NH2(+) positively-charged groups. Hence divalent dopants such as Mg, whose replacement by trivalent Al in the aluminophosphate network involves the generation of a negative charge, will tend to locate close to the NH2(+) molecular groups, suggesting that an imprinting of the organic arrangement to the spatial distribution of dopants would be feasible. Combined with the trend of ephedrine to arrange in a helicoidal fashion, an enantiomerically-pure helicoidal distribution of dopants would be expected, thus inducing a new type of chirality in microporous materials.

MILD MODIFICATION METHOD FOR THE GENERATION OF ...

African Journals Online (AJOL)

B. S. Chandravanshi

Zeolites are widely used as acid catalysts for the synthesis of fine chemicals in .... on the structural, chemical and textural properties of the mordenite samples was ..... cases, the micropore volume increased from 0.01 to 0.05 cm3g−1 and the ...

Microporous dermal-like electrospun scaffolds promote accelerated skin regeneration.

Science.gov (United States)

Bonvallet, Paul P; Culpepper, Bonnie K; Bain, Jennifer L; Schultz, Matthew J; Thomas, Steven J; Bellis, Susan L

2014-09-01

The goal of this study was to synthesize skin substitutes that blend native extracellular matrix (ECM) molecules with synthetic polymers which have favorable mechanical properties. To this end, scaffolds were electrospun from collagen I (col) and poly(ɛ-caprolactone) (PCL), and then pores were introduced mechanically to promote fibroblast infiltration, and subsequent filling of the pores with ECM. A 70:30 col/PCL ratio was determined to provide optimal support for dermal fibroblast growth, and a pore diameter, 160 μm, was identified that enabled fibroblasts to infiltrate and fill pores with native matrix molecules, including fibronectin and collagen I. Mechanical testing of 70:30 col/PCL scaffolds with 160 μm pores revealed a tensile strength of 1.4 MPa, and the scaffolds also exhibited a low rate of contraction (pores. Keratinocytes formed a stratified layer on the surface of fibroblast-remodeled scaffolds, and staining for cytokeratin 10 revealed terminally differentiated keratinocytes at the apical surface. When implanted, 70:30 col/PCL scaffolds degraded within 3-4 weeks, an optimal time frame for degradation in vivo. Finally, 70:30 col/PCL scaffolds with or without 160 μm pores were implanted into full-thickness critical-sized skin defects. Relative to nonporous scaffolds or sham wounds, scaffolds with 160 μm pores induced accelerated wound closure, and stimulated regeneration of healthy dermal tissue, evidenced by a more normal-appearing matrix architecture, blood vessel in-growth, and hair follicle development. Collectively, these results suggest that microporous electrospun scaffolds are effective substrates for skin regeneration.

Natural gas storage in microporous carbon obtained from waste of the olive oil production

Directory of Open Access Journals (Sweden)

Cecilia Solar

2008-12-01

Full Text Available A series of activated carbons (AC were prepared from waste of the olive oil production in the Cuyo Region, Argentine by two standard methods: a physical activation by steam and b chemical activation with ZnCl2. The AC samples were characterized by nitrogen adsorption at 77 K and evaluated for natural gas storage purposes through the adsorption of methane at high pressures. The activated carbons showed micropore volumes up to 0.50 cm³.g-1 and total pore volumes as high as 0.9 cm³.g-1. The BET surface areas reached, in some cases, more than 1000 m².g-1. The methane adsorption -measured in the range of 1-35 bar- attained values up to 59 V CH4/V AC and total uptakes of more than 120 cm³.g-1 (STP. These preliminary results suggest that Cuyo's olive oil waste is appropriate for obtaining activated carbons for the storage of natural gas.

Efficacy of hemostatic matrix and microporous polysaccharide hemospheres.

Science.gov (United States)

Lewis, Kevin M; Atlee, Holly; Mannone, Angela; Lin, Lawrence; Goppelt, Andreas

2015-02-01

Microporous Polysaccharide Hemospheres (MPH) are a new plant-derived polysaccharide powder hemostat. Previous studies investigated MPH as a replacement to nonflowable hemostatic agents of different application techniques (e.g., oxidized cellulose, collagen); therefore, the purpose of this study was to determine if MPH is a surrogate for flowable hemostatic agents of similar handling and application techniques, specifically a flowable thrombin-gelatin hemostatic matrix. Hemostatic efficacy was compared using a heparinized porcine abrasion model mimicking a capsular tear of a parenchymal organ. MPH (ARISTA, 1 g) and hemostatic matrix (Floseal, 1 mL) were applied, according to a randomized scheme, to paired hepatic abrasions (40 lesions per group). Hemostatic success, control of bleeding, and blood loss were assessed 2, 5, and 10 min after treatment. Hemostatic success and control of bleeding were analyzed using odds ratios and blood loss using mean differences. Hemostatic matrix provided superior hemostatic success relative to MPH at 5 (odds ratio: 0.035, 95% confidence interval: 0.004-0.278) and 10 min (0.032, 0.007-0.150), provided superior control of bleeding at 5 (0.006, <0.001-0.037) and 10 min (0.009, 0.001-0.051), and had significantly less blood loss at 5 (mean difference: 0.3118 mL/min, 95% confidence interval: 0.0939-0.5296) and 10 min (0.5025, 0.2489-0.7561). These findings corroborate other MPH investigations regarding its low-level efficacy and suggest that MPH is not an appropriate surrogate for hemostatic matrix despite similar application techniques. The lack of a procoagulant within MPH may likely be the reason for its lower efficacy and need for multiple applications. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Bottom-up synthesis of nitrogen-doped graphene sheets for ultrafast lithium storage

Science.gov (United States)

Tian, Lei-Lei; Wei, Xian-Yong; Zhuang, Quan-Chao; Jiang, Chen-Hui; Wu, Chao; Ma, Guang-Yao; Zhao, Xing; Zong, Zhi-Min; Sun, Shi-Gang

2014-05-01

A facile bottom-up strategy was developed to fabricate nitrogen-doped graphene sheets (NGSs) from glucose using a sacrificial template synthesis method. Three main types of nitrogen dopants (pyridinic, pyrrolic and graphitic nitrogens) were introduced into the graphene lattice, and an inimitable microporous structure of NGS with a high specific surface area of 504 m2 g-1 was obtained. Particularly, with hybrid features of lithium ion batteries and Faradic capacitors at a low rate and features of Faradic capacitors at a high rate, the NGS presents a superior lithium storage performance. During electrochemical cycling, the NGS electrode afforded an enhanced reversible capacity of 832.4 mA h g-1 at 100 mA g-1 and an excellent cycling stability of 750.7 mA h g-1 after 108 discharge-charge cycles. Furthermore, an astonishing rate capability of 333 mA h g-1 at 10 000 mA g-1 and a high rate cycle performance of 280.6 mA h g-1 even after 1200 cycles were also achieved, highlighting the significance of nitrogen doping on the maximum utilization of graphene-based materials for advanced lithium storage.

Bottom-up synthesis of nitrogen-doped graphene sheets for ultrafast lithium storage.

Science.gov (United States)

Tian, Lei-Lei; Wei, Xian-Yong; Zhuang, Quan-Chao; Jiang, Chen-Hui; Wu, Chao; Ma, Guang-Yao; Zhao, Xing; Zong, Zhi-Min; Sun, Shi-Gang

2014-06-07

A facile bottom-up strategy was developed to fabricate nitrogen-doped graphene sheets (NGSs) from glucose using a sacrificial template synthesis method. Three main types of nitrogen dopants (pyridinic, pyrrolic and graphitic nitrogens) were introduced into the graphene lattice, and an inimitable microporous structure of NGS with a high specific surface area of 504 m(2) g(-1) was obtained. Particularly, with hybrid features of lithium ion batteries and Faradic capacitors at a low rate and features of Faradic capacitors at a high rate, the NGS presents a superior lithium storage performance. During electrochemical cycling, the NGS electrode afforded an enhanced reversible capacity of 832.4 mA h g(-1) at 100 mA g(-1) and an excellent cycling stability of 750.7 mA h g(-1) after 108 discharge-charge cycles. Furthermore, an astonishing rate capability of 333 mA h g(-1) at 10,000 mA g(-1) and a high rate cycle performance of 280.6 mA h g(-1) even after 1200 cycles were also achieved, highlighting the significance of nitrogen doping on the maximum utilization of graphene-based materials for advanced lithium storage.

Influence of a major exposure surface on the development of microporous micritic limestones - Example of the Upper Mishrif Formation (Cenomanian) of the Middle East

Science.gov (United States)

Deville de Periere, M.; Durlet, C.; Vennin, E.; Caline, B.; Boichard, R.; Meyer, A.

2017-05-01

Microporous platform top limestones of the Cenomanian Mishrif Formation (offshore Qatar) were studied in order to investigate the diagenetic processes associated with the top-Mishrif subaerial unconformity and its influence on the development of microporosity in underlying carbonates. Petrographical and stable isotope results indicate that complex diagenetic changes occurred during subaerial exposure of the Mishrif Formation, including pervasive dissolution and meteoric cementation, as well as neomorphism of the micritic matrix. Micrites at the top of the Mishrif Formation are coarse (i.e. > 2 μm), sub-rounded and very dull luminescent under cathodoluminescence. In this uppermost part of the studied interval, the limestone matrix first underwent dissolution of unstable grains in the vadose zone, with subsequent precipitation of low-magnesium calcite (LMC) overgrowths within an oxidising phreatic setting. This process explains the poor luminescence of the micrite crystals and their relatively coarse crystallometry which results in the present day in relatively good reservoir properties. δ13C ratios within the microporous limestones are negative (up to - 4‰ V-PDB) due to the incorporation of isotopically light carbon derived from palaeosols which developed during exposure. By contrast, fine (i.e. aquifer associated with the Top-Mishrif Unconformity, and were precipitated from meteoric or mixed dysoxic waters which were slightly supersaturated with respect to calcite.

A Highly Stable Microporous Covalent Imine Network Adsorbent for Natural Gas Upgrading and Flue Gas CO2 Capture

KAUST Repository

Das, Swapan Kumar

2016-06-06

The feasible capture and separation of CO2 and N2 from CH4 is an important task for natural gas upgrading and the control of greenhouse gas emissions. Here, we studied the microporous covalent imine networks (CIN) material prepared through Schiff base condensation and exhibited superior chemical robustness under both acidic and basic conditions and high thermal stability. The material possesses a relatively uniform nanoparticle size of approximately 70 to 100 nm. This network featured permanent porosity with a high surface area (722 m2g-1) and micropores. A single-component gas adsorption study showed enhanced CO2 and CH4 uptakes of 3.32 mmol/g and 1.14 mmol/g, respectively, at 273 K and 1 bar, coupled with high separation selectivities for CO2/CH4, CH4/N2, and CO2/N2 of 23, 11.8 and 211, respectively. The enriched Lewis basicity in the porous skeletons favours the interaction of quadrupolar CO2 and polarizable CH4, resulting in enhanced CH4 and CO2 uptake and high CH4/N2, CO2/CH4 and CO2/N2 selectivities. Breakthrough experiments showed high CO2/CH4, CH4/N2 and CO2/N2 selectivities of 7.29, 40 and 125, respectively, at 298 K and 1 bar. High heats of adsorption for CH4 and CO2 (QstCH4; 32.61 kJ mol-1 and QstCO2; 42.42 kJ mol-1) provide the ultimate validation for the high selectivity. To the best of our knowledge, such a versatile adsorbent material that displays both enhanced uptake and selectivity for a variety of binary gas mixtures, including CO2/ CH4, CO2/N2 and CH4/N2, has not been extensively explored.

Preparation of micro-porous bioceramic containing silicon-substituted hydroxyapatite and beta-tricalcium phosphate.

Science.gov (United States)

Fuh, Lih-Jyh; Huang, Ya-Jing; Chen, Wen-Cheng; Lin, Dan-Jae

2017-06-01

Dimensional instability caused by sintering shrinkage is an inevitable drawback for conventional processing of hydroxyapatite (HA). A new preparation method for biphasic calcium phosphates was developed to increase micro pores and biodegradation without significant dimensional change. Powder pressed HA discs, under 100MPa, were immersed in a colloidal mixture of tetraethoxysilane (TEOS) and ammonium hydroxide for 10min, followed by drying, and then were sintered at 900°C, 1050°C, and 1200°C, respectively. Comparing with pure HA discs, the newly prepared product sintered up to 1200°C contained silicon substituted HA, beta-tricalcium phosphate, and calcium silicate with better micro-porosity, high specific surface area, less sintering shrinkage and the strength maintained. The cytocompatibility test demonstrated a better viability for D1 mice stem cells cultured on TEOS treated HA for 14days compared to the pure HA. This simple TEOS sol-gel pretreatment has the potential to be applied to any existing manufacturing process of HA scaffold for better control of sintering shrinkage, create micropores, and increase biodegradation. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and characterization of Ce doped MFI zeolite

International Nuclear Information System (INIS)

Kalita, Banani; Talukdar, Anup K.

2012-01-01

Highlights: ► Cerium was incorporated into the tetrahedral position of MFI zeolite structure. ► Unit cell volume increases with an increase of Ce content in the framework of MFI. ► A band at 310 nm in the UV–vis spectra indicates Ce incorporation in MFI structure. ► The mass loss (%) in the region 373–423 K decreases with increase of Ce in MFI. - Abstract: Ce doped MFI (mobil five) zeolites with different Si to (Ce + Al) and different Ce to Al ratios were synthesized by a hydrothermal synthesis method. All the samples were characterized by different techniques such as X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV–vis diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The results showed that almost pure MFI phase was obtained in all cases with incorporation of cerium metal into the framework. The increase in unit cell parameters observed with an increase in Ce content is indicative of incorporation of Ce into the framework structure of microporous material MFI. Corroboration of the framework incorporation of Ce into the MFI zeolite structure was also obtained from the UV–vis DRS spectra by the presence of an absorption band at 280 nm. TGA and SEM of the samples provide complementary evidence for Ce incorporation into the framework MFI structure.

Erythorbic acid promoted formation of CdS QDs in a tube-in-tube micro-channel reactor

Energy Technology Data Exchange (ETDEWEB)

Liang, Yan; Tan, Jiawei; Wang, Jiexin; Chen, Jianfeng [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Sun, Baochang, E-mail: sunbc@mail.buct.edu.cn [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Shao, Lei, E-mail: shaol@mail.buct.edu.cn [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)

2014-12-15

Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.

Synthesis of hydroxyapatite with the use of calcium carbonate as of the biological precursor; Sintese de hidroxiapatita com o uso de carbonato de calcio de origem biologica como precurssor

Energy Technology Data Exchange (ETDEWEB)

Aguilar, M.S.; Di Lello, B.C.; Queiroz, F.; Campos, N.C., E-mail: marilzasa@oi.com.br [Universidade Estacio de Sa (UESA), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia; Campos, J.B. [Universidade do Estado do Rio de Janeiro (PPGEM/UERJ), RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica

2014-07-01

This work describes the synthesis of hydroxyapatite from calcium from biological materials such as shells carbonate. In the syntheses performed, the calcium carbonate of biological origin was used as the precursor and through a precipitation reaction with phosphoric acid, was converted into calcium hydroxide. Sequentially, the precipitate was aged, filtered, washed, dried and calcined, and then transformed into hydroxyapatite. The characterization of the powders was performed by X-DR (X-ray diffraction) and SEM (scanning electron microscopy). DR-X as determined hydroxyapatite calcium phosphate phase calcium. SEM revealed a morphology of finely divided particles. The method B.E.T. showed values of specific area and volume of micropores consistent with the literature. The results of the characterizations proved feasible to use for obtaining biological hydroxyapatite materials used in the reaction conditions.(author)

Qiubin Kan

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. Qiubin Kan. Articles written in Bulletin of Materials Science. Volume 34 Issue 4 July 2011 pp 979-983. Synthesis and characterization of super-microporous material with enhanced hydrothermal stability · Shujie Wu Ke Song Jingqi Guan Qiubin Kan · More Details Abstract ...

High electrochemical capacitor performance of oxygen and nitrogen enriched activated carbon derived from the pyrolysis and activation of squid gladius chitin

Science.gov (United States)

Raj, C. Justin; Rajesh, Murugesan; Manikandan, Ramu; Yu, Kook Hyun; Anusha, J. R.; Ahn, Jun Hwan; Kim, Dong-Won; Park, Sang Yeup; Kim, Byung Chul

2018-05-01

Activated carbon containing nitrogen functionalities exhibits excellent electrochemical property which is more interesting for several renewable energy storage and catalytic applications. Here, we report the synthesis of microporous oxygen and nitrogen doped activated carbon utilizing chitin from the gladius of squid fish. The activated carbon has large surface area of 1129 m2 g-1 with microporous network and possess ∼4.04% of nitrogen content in the form of pyridinic/pyrrolic-N, graphitic-N and N-oxide groups along with oxygen and carbon species. The microporous oxygen/nitrogen doped activated carbon is utilize for the fabrication of aqueous and flexible supercapacitor electrodes, which presents excellent electrochemical performance with maximum specific capacitance of 204 Fg-1 in 1 M H2SO4 electrolyte and 197 Fg-1 as a flexible supercapacitor. Moreover, the device displays 100% of specific capacitance retention after 25,000 subsequent charge/discharge cycles in 1 M H2SO4 electrolyte.

Polarization-induced local pore-wall functionalization for biosensing: from micropore to nanopore.

Science.gov (United States)

Liu, Jie; Pham, Pascale; Haguet, Vincent; Sauter-Starace, Fabien; Leroy, Loïc; Roget, André; Descamps, Emeline; Bouchet, Aurélie; Buhot, Arnaud; Mailley, Pascal; Livache, Thierry

2012-04-03

The use of biological-probe-modified solid-state pores in biosensing is currently hindered by difficulties in pore-wall functionalization. The surface to be functionalized is small and difficult to target and is usually chemically similar to the bulk membrane. Herein, we demonstrate the contactless electrofunctionalization (CLEF) approach and its mechanism. This technique enables the one-step local functionalization of the single pore wall fabricated in a silica-covered silicon membrane. CLEF is induced by polarization of the pore membrane in an electric field and requires a sandwich-like composition and a conducting or semiconducting core for the pore membrane. The defects in the silica layer of the micropore wall enable the creation of an electric pathway through the silica layer, which allows electrochemical reactions to take place locally on the pore wall. The pore diameter is not a limiting factor for local wall modification using CLEF. Nanopores with a diameter of 200 nm fabricated in a silicon membrane and covered with native silica layer have been successfully functionalized with this method, and localized pore-wall modification was obtained. Furthermore, through proof-of-concept experiments using ODN-modified nanopores, we show that functionalized nanopores are suitable for translocation-based biosensing.

Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing

Science.gov (United States)

2007-09-30

Polyimide Insulated Electrical Wire", SAMPE pp.16, Jan/Feb 1984. 11. Brown, S. R.; Deluccia, J.J., " Galvanic Corrosion Fatigue Testing of 7075-T6...Modified Microporous Aluminosilicate" Development of Adsorbents for Air and Water Treatment Conference, 226th American Chemical Society (ACS) National

Evaluation of alignment error of micropore X-ray optics caused by hot plastic deformation

Science.gov (United States)

Numazawa, Masaki; Ishi, Daiki; Ezoe, Yuichiro; Takeuchi, Kazuma; Terada, Masaru; Fujitani, Maiko; Ishikawa, Kumi; Nakajima, Kazuo; Morishita, Kohei; Ohashi, Takaya; Mitsuda, Kazuhisa; Nakamura, Kasumi; Noda, Yusuke

2018-06-01

We report on the evaluation and characterization of micro-electromechanical system (MEMS) X-ray optics produced by silicon dry etching and hot plastic deformation. Sidewalls of micropores formed by etching through a silicon wafer are used as X-ray reflecting mirrors. The wafer is deformed into a spherical shape to focus parallel incidence X-rays. We quantitatively evaluated a mirror alignment error using an X-ray pencil beam (Al Kα line at 1.49 keV). The deviation angle caused only by the deformation was estimated from angular shifts of the X-ray focusing point before and after the deformation to be 2.7 ± 0.3 arcmin on average within the optics. This gives an angular resolution of 12.9 ± 1.4 arcmin in half-power diameter (HPD). The surface profile of the deformed optics measured using a NH-3Ns surface profiler (Mitaka Kohki) also indicated that the resolution was 11.4 ± 0.9 arcmin in HPD, suggesting that we can simply evaluate the alignment error caused by the hot plastic deformation.

The use of a micropore particle technology in the treatment of acute wounds.

Science.gov (United States)

Ryan, E

2017-07-02

A clinical audit was performed to evaluate whether Acapsil micropore particle technology (MPPT) powder could improve the management of acute wounds to heal by secondary intention. Wounds, which could be characterised as sloughy, wet and probably infected, normally managed by debridement followed by negative pressure wound therapy (NPWT), were included in the evaluation. The MPPT powder was applied topically to the wound surface either once daily or on alternate days, with each wound receiving a total of two to five applications. Most patients had NPWT after the MPPT powder treatment had finished to assist healing. The study included nine patients with dehisced surgical wounds and one with a category IV pressure ulcer (PU). The wounds were generally covered in slough, exudate and showing signs of local infection. The topical MPPT powder rapidly desloughed the wounds, controlled exudate levels, promoted granulation and was well tolerated. All wounds proceeded towards closure. Comparison of the present data with MPPT powder to standard treatment suggests that the speed of healing using MPPT was improved. Further examination is required to determine if this reduces dressing changes, nursing time, and financial cost.

A scalable, micropore, platelet rich plasma separation device.

Science.gov (United States)

Dickson, Mary Nora; Amar, Levy; Hill, Michael; Schwartz, Joseph; Leonard, Edward F

2012-12-01

We have designed a novel, low energy platelet-rich-plasma (PRP) separator capable of producing 50 mL of PRP in 30 min, intended for military and emergency applications. Blood flows over a 3 mm length of sieve at high rates of shear. A plasma-platelet filtrate passes through the sieve's pores while erythrocytes remain. The filtrate is flowed over a second 3 mm length of smaller-pored sieve that withdraws plasma. Bulk blood volume is maintained by returning platelet-free plasma to the erythrocyte pool, enabling a nearly complete multi-pass platelet extraction. The total percentage of platelets extracted is:θ(T)=1-exp (-V(f)(T)Φ(P)/V) where V is the original plasma volume, V ( f )(T) is the total filtered volume, and ϕ ( P ) is platelet passage ratio (filtrate concentration/bulk average concentration) taken to be constant. Maximum θ(T) occurs at maximum V ( f )(T)× ϕ ( P ) Test microsieves, 3 mm long × 3 mm wide, were used. ϕ ( P ) values measured at various filtrate flow rates (20-100 uL/min) and utilizing various filter pore sizes (1.2-3.5 μm), was as high as 150 %. Maximum V ( f )(T)× ϕ ( P ) was achieved utilizing the 3.5 um filters at the highest flow rate, 100 uL/min. Erythrocyte leakages were always below 2,000/uL, far below the allowable limit stipulated by the American Association of Blood Banking. These data imply that a 13.7 cm(2) filter area is sufficient to achieve the target separation of 50 mL of platelet concentrate in 30 min. The filtration cartridge would consist of multiple microporous strips of 3 mm width arranged in parallel so that each element would see the conditions used in the prototype experiments presented here. Other microfiltration schemes suggest no method of scaling to practical levels.

Enhanced catalytic activity through the tuning of micropore environment and supercritical CO2 processing: Al(porphyrin)-based porous organic polymers for the degradation of a nerve agent simulant.

Science.gov (United States)

Totten, Ryan K; Kim, Ye-Seong; Weston, Mitchell H; Farha, Omar K; Hupp, Joseph T; Nguyen, SonBinh T

2013-08-14

An Al(porphyrin) functionalized with a large axial ligand was incorporated into a porous organic polymer (POP) using a cobalt-catalyzed acetylene trimerization strategy. Removal of the axial ligand afforded a microporous POP that is catalytically active in the methanolysis of a nerve agent simulant. Supercritical CO2 processing of the POP dramatically increased the pore size and volume, allowing for significantly higher catalytic activities.

Synthesis of polybenzoxazine based nitrogen-rich porous carbons for carbon dioxide capture

Science.gov (United States)

Wan, Liu; Wang, Jianlong; Feng, Chong; Sun, Yahui; Li, Kaixi

2015-04-01

Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m2 g-1, a large pore volume of 0.15-0.65 cm3 g-1, tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount of the soft-templating agent F127 has multiple influences on the textural and chemical properties of the carbons, affecting the surface area and pore structure, impacting the compositions of nitrogen species and resulting in an improvement of the CO2 capture performance. At 1 bar, high CO2 uptake of 4.02 and 6.35 mmol g-1 at 25 and 0 °C was achieved for the sample NPC-2 with a molar ratio of F127 : urea = 0.010 : 1. This can be attributed to its well-developed micropore structure and abundant pyridinic nitrogen, pyrrolic nitrogen and pyridonic nitrogen functionalities. The sample NPC-2 also exhibits a remarkable selectivity for CO2/N2 separation and a fast adsorption/desorption rate and can be easily regenerated. This suggests that the polybenzoxazine-based NPCs are desirable for CO2 capture because of possessing a high micropore surface area, a large micropore volume, appropriate pore size distribution, and a large number of basic nitrogen functionalities.Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m2 g-1, a large pore volume of 0.15-0.65 cm3 g-1, tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount of the soft-templating agent F127 has multiple influences on the textural and chemical properties of the carbons, affecting the surface area and pore structure, impacting the compositions of nitrogen species and resulting in an improvement of the