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1.
ACS Omega ; 7(15): 12971-12977, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35474795

RESUMO

Nowadays, the increase in plastic waste is causing serious environmental problems. Catalytic cracking has been considered a promising candidate to solve these problems. Catalytic cracking has emerged as an attractive process that can produce valuable products from plastic wastes. Solid acid catalysts such as zeolites decompose the plastic waste at a lower temperature. The lower decomposition temperature may be desirable for practical use. Herein, we synthesized both Zr- and Al-incorporated Beta zeolite using amorphous ZrO2-SiO2. The optimized Zr content in the dry gel allowed the enhancement of Lewis acidity without a significant loss of Brønsted acidity. The enhancement of Lewis acidity was mainly due to Zr species incorporated into the zeolite framework. Thanks to the enhanced Lewis acidity without any significant loss of Brønsted acidity, higher polymer decomposition efficiency was achieved than a conventional Beta zeolite.

2.
Sci Rep ; 9(1): 14889, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31624360

RESUMO

The high density nucleation of α-Al2O3 nanocrystallites was observed by rapid heating of the aluminum formate hydroxide-based precursor powder at 1200 °C for 50 s. The nucleation of α-Al2O3 nanocrystallites with less 10 nm in size from high purity aluminum oxide matrix has not been observed to our knowledge. Based on the results of XRD and TEM, α-Al2O3 nanocrystallites nucleated from the amorphous phase which formed after thermal decomposition of the precursor powder. Subsequently, α-Al2O3 with hollow rod-like morphology formed through coalescence and growth of nanocrystallites after heating at 1200 °C for 1 min. The results obtained in this paper indicates a possible beneficial effect of the rapid heating and cooling of the aluminum formate hydroxide-based precursor powder on the precipitation of α-Al2O3 nanocrystallites.

3.
Membranes (Basel) ; 9(7)2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31319501

RESUMO

Hydrophobic pure-silica *BEA-type zeolite membranes with large pores were prepared on tubular silica supports by hydrothermal synthesis using a secondary growth method and were applied to the separation of alcohol/water mixtures by pervaporation (PV), an alternative energy-efficient process for production of biofuels. Amorphous pure-silica tubular silica supports, free of Al atoms, were used for preparing the membranes. In this study, the effects of the synthesis conditions, such as the H2O/SiO2 and NH4F/SiO2 ratios in the synthetic gel, on the membrane formation process and separation performance were systematically investigated. The successfully prepared dense and continuous membranes exhibited alcohol selectivity and high flux for the separation of ethanol/water and butanol/water mixtures. The pure-silica *BEA membranes obtained under optimal conditions (0.08SiO2:0.5TEAOH:0.7NH4F:8H2O) showed high PV performance with a separation factor of 229 and a flux of 0.62 kg·m-2·h-1 for a 1 wt % n-butanol/water mixture at 318 K. This result was attributed to the hydrophobicity and large pore size of the pure-silica *BEA membrane. This was the first successful synthesis of hydrophobic large-pore zeolite membranes on tubular supports with alcohol selectivity, and the obtained results could provide new insights into the research on hydrophobic membranes with high permeability.

4.
Membranes (Basel) ; 9(4)2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30939830

RESUMO

Silicalite-1 membranes with high pervaporation performance were prepared successfully on a silica-particle-coated tubular silica support using a gel-free steam-assisted conversion (SAC) method. The effects of the silica-particle layer formed on the top surface of the silica support and the physical properties of the silica particles themselves on the membrane-formation process were investigated. The silica particles coated served as the additional silica source for growing the silicalite-1 seed crystal layer into the silicalite-1 membrane. As a result, it was possible to form a dense and continuous membrane even under gel-free conditions. Furthermore, it was found that the properties of the silica particles, such as their primary particle diameter, had a determining effect on their solubility during the steam treatment, that is, on the supply rate of the silica source. The silicalite-1 membrane obtained using the spherical-silica-particle-coated support had an approximately 9-µm-thick separation layer and showed very high pervaporation performance, exhibiting a separation factor of 105 and a flux of 3.72 kg m-2 h-1 for a 10 wt % ethanol/water mixture at 323 K. Thus, the gel-free SAC method can be used with a silica support coated with silica particles to readily prepare high-performance membranes without producing any chemical waste.

5.
Pathol Int ; 69(4): 229-234, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30775827

RESUMO

A 73-year-old Japanese man, who worked at a confectionery company for more than 20 years, was diagnosed with a 28 mm nodular lesion in the superior lobe of the right lung by whole-body computed tomography examination. A biopsy revealed the presence of adenocarcinoma. With a diagnosis of a primary lung cancer, a right upper lobectomy was performed. A nodular lesion, 25 × 23 mm in size, was observed in the upper right lobe lung field, and was diagnosed histopathologically as a papillary adenocarcinoma. In addition, fibrous scars in the central part of the tumor showed numerous Langhans and/or foreign body giant cells, and histiocytic cells that had phagocytized numerous small transparent crystals, together with coal powder deposition. The extracted crystals were observed with a scanning electron microscope, and although plate-like structures were observed, ferruginous bodies suggestive of asbestos were not found. The crystals were demonstrated to be talc by powder X-ray diffraction. Herein, we investigated a case of lung adenocarcinoma in a patient with talcosis, with discussions based on a literature search. This collision of talcosis and lung adenocarcinoma adds to an increasing body of knowledge on an apparent association between talc and cancer cases.


Assuntos
Adenocarcinoma de Pulmão/diagnóstico por imagem , Poluentes Ocupacionais do Ar/efeitos adversos , Neoplasias Pulmonares/diagnóstico por imagem , Exposição Ocupacional , Pneumoconiose/diagnóstico por imagem , Talco/efeitos adversos , Adenocarcinoma de Pulmão/complicações , Adenocarcinoma de Pulmão/patologia , Idoso , Biópsia , Doces , Diagnóstico Diferencial , Humanos , Pulmão/patologia , Neoplasias Pulmonares/complicações , Neoplasias Pulmonares/patologia , Masculino , Microscopia Eletrônica de Varredura , Pneumoconiose/complicações , Pneumoconiose/patologia , Tomografia Computadorizada por Raios X , Difração de Raios X
6.
ChemSusChem ; 11(11): 1756-1760, 2018 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-29673091

RESUMO

Dehumidification in CO2 adsorptive separation processes is an important issue, owing to its high energy consumption. However, available adsorbents such as low-silica zeolites show a significant decrease in CO2 adsorption capacity when water vapor is present. A core-shell-structured MFI-type zeolite with a hydrophilic ZSM-5 coated with a hydrophobic silicalite-1 shell layer was applied in CO2 adsorptive separation under wet conditions. This hybrid material demonstrated remarkably high water tolerance with stable CO2 adsorption performance without additional thermal treatment for regeneration, whereas a significant decrease in the CO2 adsorption amount because of water vapor was observed on the parent ZSM-5. The core-shell structure of zeolites with high pore volumes, such as LTA or CHA, could also be suitable candidates for high CO2 adsorption capacity and high water tolerance for practical applications.

7.
ACS Appl Mater Interfaces ; 7(43): 24360-9, 2015 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-26479449

RESUMO

The attractive properties of zeolites, which make them suitable for numerous applications for the energy and chemical industries and for life sciences, are derived from their crystalline framework structures. Herein, we describe the rational synthesis of a microporous material, HUS-10, utilizing a layered silicate precursor, HUS-2, as a structural building unit. For the ordered micropores to be formed, interlayer pillars that supported the original silicate layer of HUS-2 were immobilized through the interlayer silylation of silanol groups with trichloromethylsilane and a subsequent dehydration-condensation reaction of the hydroxyl groups on the preintroduced tetrahedral units. An actual molecular sieving ability, enabling the adsorption of molecules smaller than ethane, was confirmed in the ordered micropores of HUS-10. The hydrophilic adsorption could also be controlled by changing the number of methyl and hydroxyl groups in the immobilized interlayer pillars. In addition, when the adsorption behaviors of CO2, CH4, and N2 on HUS-10 were compared to those on siliceous MFI and CDO zeolites with approximately the same pore diameter, the CO2 adsorption capacity of HUS-10 was comparable. Conversely, because of the adsorption inhibition of CH4 and N2, HUS-10 exhibited larger CO2/CH4 and CO2/N2 adsorption ratios relative to those of MFI and CDO zeolites. These results reveal that the unique microporous framework structure presented by the rational structural design using the layered silicate precursor HUS-2 has the potential to separate CO2 from gas mixtures.

8.
PLoS One ; 9(8): e103818, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25133692

RESUMO

Diabetes is a crucial risk factor for stroke and is associated with increased frequency and poor prognosis. Although endothelial dysfunction is a known contributor of stroke, the underlying mechanisms have not been elucidated. The aim of this study was to elucidate the mechanism by which chronic hyperglycemia may contribute to the worsened prognosis following stroke, especially focusing on mitochondrial alterations. We examined the effect of hyperglycemia on hemorrhagic transformation at 24 hours after middle cerebral artery occlusion (MCAO) in streptozotocin (STZ) -induced diabetic mice. We also examined the effects of high-glucose exposure for 6 days on cell death, mitochondrial functions and morphology in human brain microvascular endothelial cells (HBMVECs) or human endothelial cells derived from induced pluripotent stem cells (iCell endothelial cells). Hyperglycemia aggravated hemorrhagic transformation, but not infarction following stroke. High-glucose exposure increased apoptosis, capase-3 activity, and release of apoptosis inducing factor (AIF) and cytochrome c in HBMVECs as well as affected mitochondrial functions (decreased cell proliferation, ATP contents, mitochondrial membrane potential, and increased matrix metalloproteinase (MMP)-9 activity, but not reactive oxygen species production). Furthermore, morphological aberration of mitochondria was observed in diabetic cells (a great deal of fragmentation, vacuolation, and cristae disruption). A similar phenomena were seen also in iCell endothelial cells. In conclusion, chronic hyperglycemia aggravated hemorrhagic transformation after stroke through mitochondrial dysfunction and morphological alteration, partially via MMP-9 activation, leading to caspase-dependent apoptosis of endothelial cells of diabetic mice. Mitochondria-targeting therapy may be a clinically innovative therapeutic strategy for diabetic complications in the future.


Assuntos
Apoptose , Isquemia Encefálica/patologia , Hemorragia Cerebral/patologia , Diabetes Mellitus Experimental/complicações , Células Endoteliais/fisiologia , Animais , Células Cultivadas , Endotélio Vascular/patologia , Glucose/fisiologia , Humanos , Hiperglicemia/complicações , Masculino , Potencial da Membrana Mitocondrial , Camundongos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Forma das Organelas , Prognóstico
9.
Inorg Chem ; 50(6): 2294-301, 2011 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-21294579

RESUMO

A new layered silicate, HUS-1, was synthesized by hydrothermal synthesis using decomposed FAU- and *BEA-type zeolites as nanosized silica parts. Structural analyses by X-ray powder diffractometry and solid-state magic-angle-spinning (MAS) NMR spectroscopy revealed that HUS-1 has a layered structure containing a silicate layer per unit cell along a stacking direction. Its framework topology is similar to that of SOD-type zeolites and consists of a halved sodalite cage, which includes four- and six-membered Si rings. Structure refinement by the Rietveld method showed that tetramethylammonium (TMA) ions used as a structure-directing agent (SDA) were incorporated into the interlayer. The four methyl groups of the TMA molecule were located orderly in a hemispherical cage in the silicate layer, which suggests restraint of molecular motion. The interlayer distance is estimated at about 0.15 nm, which is unusually short in comparison with that in other layered silicates (e.g., ß-HLS or RUB-15) with similar framework topologies. The presence of hydrogen bonding between adjacent terminal O atoms was clearly revealed by the (1)H MAS NMR spectroscopy and by electron-density distribution obtained by the maximum entropy method.


Assuntos
Silicatos/química , Silicatos/síntese química , Modelos Moleculares , Estrutura Molecular , Tamanho da Partícula , Difração de Pó
10.
J Nanosci Nanotechnol ; 9(1): 627-33, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19441359

RESUMO

A lamellar material composed of alternating layers of magnesium phosphate sheets and n-hexadecylammonium (n-C16H33NH3+) ions was synthesized by the reaction between magnesium acetate tetrahydrate and phosphoric acid. The chemical formula of the composite material was determined to be (n-C16H33NH3+)Mg2+(HPO4(2-))(H2PO4-) by ICP, TG, and 31P MAS NMR measurements. The lamellar composite was obtained under basic conditions adjusted with tetramethylammonium (TMAOH) and tetraethylammonium hydroxides (TEAOH), while ammonium ions did not act as an alkali source useful for obtaining the composite material. The formation of crystalline byproducts such as hydrated newberyite (MgHPO4.3H2O) and ammonium-type struvite (MgNH4PO4. 6H2O) was suppressed by using the EtOH/H2O mixed solution and by adding TMAOH and TEAOH to adjust the synthetic condition, respectively. Including the data on calcium, barium and strontium phosphates, we can totally understand the formation of the mesostructured materials composed of ionic frameworks in the presence of n-alkylamines in detail. It is quite important to suppress the formation of crystalline alkaline earth metal phosphates and control the solubilities of reactants and products for synthesizing pure mesostructured materials with ionically crosslinked frameworks.

11.
Langmuir ; 24(22): 13113-20, 2008 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-18947246

RESUMO

Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0).


Assuntos
Fosfatos de Cálcio/química , Ácidos Carboxílicos/química , Tensoativos/química , Ânions , Cálcio/química , Ácido Glutâmico/química , Teste de Materiais , Microscopia Eletrônica de Transmissão , Estrutura Molecular , Ácido Palmítico/química , Fosfatos/química , Poliaminas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Difração de Raios X
13.
J Am Chem Soc ; 126(32): 9914-5, 2004 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-15303853

RESUMO

The anisotropically phase-segregated CoPd sulfide nanoparticles, named "CoPd nanoacorns", were spontaneously generated by reducing the corresponding metal precursors with 1,2-hexadecanediol in the presence of various alkanethiols. The CoPd nanoacorn consisting of crystalline Co9S8 and amorphous PdSx phases with the Co9S8 (001) plane at their interface was found to spontaneously form through the anisotropic growth of the Co9S8 phase after the generation of PdSx nanoparticles.

14.
J Am Chem Soc ; 125(29): 8708-9, 2003 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-12862449

RESUMO

In the present work, a novel method was developed for the fabrication of 2D superlattices with different symmetries. Same-surface amino-functionalized Au nanoparticles as building blocks were self-assembled to form different 2D superlattices using surface modification with organic acids. The 2D superlattices of quasi-honeycomb and square structures were obtained by neutralizing amino-functionalized Au nanoparticles with 1,3,5-tribenzenecarboxylic acid and acetic acid, respectively. These results strongly suggest that the different types of 2D or 3D superlattices can be constructed by simple addition of proper acid to nanoparticles functionalized with amino groups. This method will allow us to obtain various desired metal superlattices without fully synthesizing the ligands.

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