Targeted Synthesis of Nanostructured Oxide Materials

2007 ◽  
Vol 1056 ◽  
Author(s):  
Greta Ricarda Patzke ◽  
Ying Zhou
Keyword(s):  
Hydrothermal Process ◽  
Kinetic Studies ◽  
Complex Oxide ◽  
Morphology Control ◽  
Oxide Materials ◽  
New Materials ◽  
Binary Oxides ◽  
Nanostructured Oxide ◽  
One Step ◽  
The One

ABSTRACTMorphology control is a key challenge in the straightforward hydrothermal production of technologically relevant anisotropic oxide materials. The use of readily available ionic additives as growth modifiers is discussed and compared for molybdenum- and tungsten oxide-based systems, and it is extended upon the formation of ternary W/Mo-oxides. Generally, the one-step hydrothermal synthesis of ternary and higher oxides is an important goal, because their properties often outperform those of the binary oxides. This holds especially for the Bi2O3-MoO3-VOx (BIMOVOx) system as a rich source of new materials. We present a new solution-based approach to α-Bi2O3 nanobelts starting from commercial Bi2O3 and K2SO4 as a key step on the way to anisotropic BIMOVOx-oxides. This hydrothermal process is an illustrative example of highly selective and efficient morphology control through an inorganic additive. As mechanistic and kinetic studies are crucial for the design of complex oxide nanomaterials, the Bi2O3-K2SO4 system is compared to our previous studies on Mo-, W- and V-oxides with respect to its hydrothermal parameter window and robustness.

scholarly journals A Novel Dimeric Exoglucanase (GH5_38): Biochemical and Structural Characterisation towards its Application in Alkyl Cellobioside Synthesis

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 746 ◽  
Author(s):  
Mpho S. Mafa ◽  
Heinrich W. Dirr ◽  
Samkelo Malgas ◽  
Rui W. M. Krause ◽  
Konanani Rashamuse ◽  
...  
Keyword(s):  
Glycoside Hydrolase ◽  
Kinetic Studies ◽  
Glycoside Hydrolase Family ◽  
Primary Alcohols ◽  
Structural Characterisation ◽  
Alkyl Glycosides ◽  
Glycoside Synthesis ◽  
One Step ◽  
Ph Range ◽  
The One

An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked β-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards β-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s−1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s−1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% β-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography–mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.

scholarly journals Hydrothermal synthesis of anisotropic alkali and alkaline earth vanadates

2007 ◽  
Vol 22 (1) ◽  
pp. 5-18 ◽  
Author(s):  
Alexej Michailovski ◽  
Michael Wörle ◽  
Denis Sheptyakov ◽  
Greta R. Patzke
Keyword(s):  
Hydrothermal Synthesis ◽  
Systematic Study ◽  
Alkaline Earth ◽  
Hydrothermal Process ◽  
Vanadium Oxides ◽  
Hydrothermal Systems ◽  
Oxide Materials ◽  
Emerging Trends ◽  
One Step ◽  
Systematic Field

In the course of a systematic field study, anisotropic alkali and alkaline earth vanadates have been accessed through a straightforward, one-step hydrothermal process. They are formed quantitatively from V2O5 and alkali- or alkaline earth halide solutions after a few days of autoclave treatment in the temperature range between 100 and 220 °C. The presence of ionic additives leads to an interplay between the formation of isotropic crystalline phases and the production of fibrous oxide materials, such as a novel magnesium vanadate. The influence of the hydrothermal parameters and of the alkali/alkaline earth halides on the emerging phases and morphologies has been investigated in the course of a systematic study. The results are compared with other vanadate- and transition metal oxide-based hydrothermal systems, and the emerging trends are discussed with respect to the development of predictive synthetic concepts for nanostructured vanadium oxides.

scholarly journals Electrochemical Oxidation of Ti15Mo Alloy—The Impact of Anodization Parameters on Surface Morphology of Nanostructured Oxide Layers

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 68
Author(s):  
Magdalena Jarosz ◽  
Leszek Zaraska ◽  
Marcin Kozieł ◽  
Wojciech Simka ◽  
Grzegorz D. Sulka
Keyword(s):  
Surface Morphology ◽  
Pure Titanium ◽  
Elemental Content ◽  
Potential Range ◽  
Oxide Layers ◽  
X Ray ◽  
Nanostructured Oxide ◽  
One Step ◽  
The One ◽  
The Impact

It is well-known that the structure and composition of the material plays an important role in the processes occurring at the surface. In this paper, a surface morphology of nanostructured oxide layers electrochemically grown on Ti15Mo, tuned by applying different anodization parameters, was investigated in detail. The one-step anodization of Ti15Mo alloy was performed at room temperature in an ethylene glycol-based electrolyte containing 0.11 M NH4F and 1.11 M H2O. Different anodization times (ranging from 5 to 60 min) and applied potentials (40–100 V) were tested, and the surface morphology, elemental content, and crystalline structure were monitored by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffractometry (XRD), respectively. The results showed that contrary to the multistep anodization of titanium foil, the surface morphology of anodic oxide obtained via the one-step process contains the nanoporous outer layer covering the nanotubular structure. What is more, the pore diameter (Dp) and interpore distance (Dint) of such layers exhibit different trends than those observed for anodization of pure titanium. In particular, at a certain potential range, a decrease in both Dp and Dint with increasing potential was observed. However, independently on the used anodization conditions, the elemental content of oxide layers remained similar, showing the amount of molybdenum at c.a. 15 wt.%. Finally, the amorphous nature of as-anodized layers was confirmed, and their optical band-gap was determined from the diffuse reflectance UV–Vis spectra. It was found that Eg is tunable to some extent by changing the anodizing potential. However, further thermal treatment in air at 400 °C resulted in the anatase phase formation that was accompanied by a significant Eg reduction. Therefore, we believe that the presented results will greatly contribute to the understanding of anodic formation of nanostructured functional oxide layers with tunable properties that can be applied in various fields.

scholarly journals Synthesis of Silver Nanoparticles through Orange Peel Powder for Antibacterial Composite Filler Applications

2021 ◽  
Author(s):  
Rathinavel Subbiah ◽  
S. S. Saravanakumar
Keyword(s):  
Silver Nanoparticles ◽  
Thermal Analyses ◽  
Hydrothermal Process ◽  
Orange Peel ◽  
Filler Materials ◽  
Gram Positive Bacteria ◽  
One Step ◽  
Ft Ir ◽  
Composite Filler ◽  
The One

Abstract Environmental concerns and the positive aspects of biowaste materials gained the attention of researchers to use them as filler materials in fabricating of green composites along with polymer matrices, but most of them are not suitable for extensive applications in high thermal applications. In most of the natural particulate materials are not having the ability to fight against pathogens. To overcome such barriers, a modification of biowaste - Orange Peel Powder (OPP) by the generation of silver nanoparticles (AgNPs) is prepared with the one-step hydrothermal process. The modified Orange Peel Powder (MOPP), is then characterized by FESEM, EDX, FT-IR, XRD, and Thermal analyses. The presence of AgNPs in the MOPP is confirmed through FESEM & EDX analysis. FT-IR spectral analysis pronounced the non mutate functional groups in MOPP as compared with OPP. The generation of AgNPs in MOPP is confirmed through the XRD peaks of reflection planes at (1,1,1), (2,0,0), (2,2,0) & (3,1,1). Thermal Analysis results of TGA and DSC show the MOPP has increased thermal stability up to 363°C. Antibacterial test against Gram-negative and Gram-positive bacteria for OPP & MOPP shows the inclusion of Ag strongly objects the pathogens. Eventually, the MOPP can be utilized as filler material along with the polymer matrix in high thermal as well as antibacterial composite filler applications.

“Channeling” the powers of God’s Word

2010 ◽  
Vol 4 (2) ◽  
pp. 135-156 ◽  
Author(s):  
Dorothea E. Schulz
Keyword(s):  
The Other ◽  
Border Zone ◽  
Focus Attention ◽  
Spiritual Power ◽  
New Materials ◽  
God's Word ◽  
Audio Recordings ◽  
Heated Debate ◽  
The Subject ◽  
The One

Starting with the controversial esoteric employment of audio recordings by followers of the charismatic Muslim preacher Sharif Haidara in Mali, the article explores the dynamics emerging at the interface of different technologies and techniques employed by those engaging the realm of the Divine. I focus attention on the “border zone” between, on the one hand, techniques for appropriating scriptures based on long-standing religious conventions, and, on the other, audio recording technologies, whose adoption not yet established authoritative and standardized forms of practice, thereby generating insecurities and becoming the subject of heated debate. I argue that “recyclage” aptly describes the dynamics of this “border zone” because it captures the ways conventional techniques of accessing the Divine are reassessed and reemployed, by integrating new materials and rituals. Historically, appropriations of the Qur’an for esoteric purposes have been widespread in Muslim West Africa. These esoteric appropriations are at the basis of the considerable continuities, overlaps and crossovers, between scripture-related esoteric practices on one side, and the treatment by Sharif Haidara’s followers of audio taped sermons as vessels of his spiritual power, on the other.

A Series of Metal-Organic Frameworks for Selective CO2 Capture and Catalytic Oxidative Carboxylation of Olefins

2018 ◽  
Author(s):  
Huong T. D. Nguyen ◽  
Y B. N. Tran ◽  
Hung N. Nguyen ◽  
Tranh C. Nguyen ◽  
Felipe Gándara ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gas Adsorption ◽  
New Materials ◽  
One Pot ◽  
Acid Gas ◽  
Naphthalene Diimide ◽  
Styrene Carbonate ◽  
Metal Organic ◽  
Adsorption Of Co ◽  
The One

<p>Three novel lanthanide metal˗organic frameworks (Ln-MOFs), namely MOF-590, -591, and -592 were constructed from a naphthalene diimide tetracarboxylic acid. Gas adsorption measurements of MOF-591 and -592 revealed good adsorption of CO<sub>2</sub> (low pressure, at room temperature) and moderate CO<sub>2</sub> selectivity over N<sub>2</sub> and CH<sub>4</sub>. Accordingly, breakthrough measurements were performed on a representative MOF-592, in which the separation of CO<sub>2</sub> from binary mixture containing N<sub>2</sub> and CO<sub>2</sub> was demonstrated without any loss in performance over three consecutive cycles. Moreover, MOF-590, MOF-591, and MOF-592 exhibited catalytic activity in the one-pot synthesis of styrene carbonate from styrene and CO<sub>2</sub> under mild conditions (1 atm CO<sub>2</sub>, 80 °C, and solvent-free). Among the new materials, MOF-590 revealed a remarkable efficiency with exceptional conversion (96%), selectivity (95%), and yield (91%). </p><br>

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

2020 ◽  
Vol 24 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Zita Rádai ◽  
Réka Szabó ◽  
Áron Szigetvári ◽  
Nóra Zsuzsa Kiss ◽  
Zoltán Mucsi ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Room Temperature ◽  
Phase Transfer ◽  
One Pot ◽  
Substrate Dependence ◽  
Triethylbenzylammonium Chloride ◽  
One Step ◽  
The Pudovik Reaction ◽  
The One ◽  
Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

scholarly journals One-Year Clinical Evaluation of the Bonding Effectiveness of a One-Step, Self-Etch Adhesive in Noncarious Cervical Lesion Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Babacar Faye ◽  
Mouhamed Sarr ◽  
Khaly Bane ◽  
Adjaratou Wakha Aidara ◽  
Seydina Ousmane Niang ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Retention Rate ◽  
Recall Rate ◽  
Acid Etching ◽  
Significant Difference ◽  
Usphs Criteria ◽  
One Step ◽  
One Year ◽  
The One ◽  
Self Etch

This study evaluated the one-year clinical performance of a one-step, self-etch adhesive (Optibond All-in-One, Kerr, CA, USA) combined with a composite (Herculite XRV Ultra, Kerr Hawe, CA, USA) to restore NCCLs with or without prior acid etching. Restorations performed by the same practitioner were evaluated at baseline and after 3, 6, and 12 months using modified USPHS criteria. At 6 months, the recall rate was 100%. The retention rate was 84.2% for restorations with prior acid etching, but statistically significant differences were observed between baseline and 6 months. Without acid etching, the retention rate was 77%, and no statistically significant difference was noted between 3 and 6 months. Marginal integrity (93.7% with and 87.7% without acid etching) and discoloration (95.3% with and 92.9% without acid etching) were scored as Alpha or Bravo, with better results after acid etching. After one year, the recall rate was 58.06%. Loss of pulp vitality, postoperative sensitivity, or secondary caries were not observed. After one year retention rate was of 90.6% and 76.9% with and without acid conditioning. Optibond All-in-One performs at a satisfactory clinical performance level for restoration of NCCLs after 12 months especially after acid etching.

scholarly journals Building up cyclodextrins from scratch – templated enzymatic synthesis of cyclodextrins directly from maltose

2021 ◽  
Author(s):  
Dennis Larsen ◽  
Sophie R. Beeren
Keyword(s):  
Enzymatic Synthesis ◽  
Combinatorial Libraries ◽  
One Step ◽  
The One ◽  
Kinetic Trapping

Template-induced kinetic trapping of specific cyclodextrins in enzyme-mediated dynamic combinatorial libraries of linear and cyclic α-glucans enables the one-step synthesis of cyclodextrins from maltose in water.

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