Investigation of Factors Influencing the Formation of Tungstate-Based Inorganic-Organic Hybrid Nanobelts/Nanotubes

2007 ◽  
Vol 352 ◽  
pp. 85-88 ◽  
Author(s):  
De Liang Chen ◽  
Yoshiyuki Sugahara
Keyword(s):  
Reaction Rate ◽  
Molar Ratio ◽  
Long Range Order ◽  
Interlayer Water ◽  
Organic Hybrid ◽  
Lamellar Structures ◽  
Factors Influencing ◽  
Wide Range ◽  
Formation Behavior ◽  
Apparent Diameter

Tungstate-based inorganic−organic hybrid nanobelts/nanotubes were synthesized in a system of H2W2O7·xH2O/n-octylamine/heptane (n-octylamine:H2W2O7·xH2O molar ratio: 30), and the effects of the volume ratios of heptane to n-octylamine and the amounts of interlayer water in H2W2O7·xH2O on the formation behavior of the hybrids were investigated. The belt/tubelike hybrids obtained were 10–20 +m in length and 200–500 nm in apparent diameter. Large volume ratios of heptane to n-octylamine not only enhanced the degree of the long-range order of the lamellar structures in the hybrids, but they also improved the morphologic uniformity of the hybrids. The existence of interlayer water in H2W2O7·xH2O was indispensable to the formation of tungstate-based inorganic−organic hybrid nanobelts/nanotubes. The amounts of interlayer water in H2W2O7·xH2O varied over a wide range (x, from 0.85 to 4.1), had a neglectable effect on the morphology of the tungstate-based nanophase hybrids, but exerted a remarkable influence on the rate of the reaction of H2W2O7·xH2O with n-octylamine in the heptane solvent. The larger the amount of interlayer water, the more rapid the reaction rate.

scholarly journals Promising Immobilization of Industrial-Class Phospholipase A1 to Attain High-Yield Phospholipids Hydrolysis and Repeated Use with Optimal Water Content in Water-in-Oil Microemulsion Phase

2021 ◽  
Vol 11 (4) ◽  
pp. 1456
Author(s):  
Yusuke Hayakawa ◽  
Ryoichi Nakayama ◽  
Norikazu Namiki ◽  
Masanao Imai
Keyword(s):  
Water Content ◽  
Reaction Rate ◽  
Enzyme Reaction ◽  
Initial Reaction Rate ◽  
Industrial Applications ◽  
Molar Ratio ◽  
High Yield ◽  
Initial Reaction ◽  
Phospholipase A1 ◽  
Repeated Use

In this study, we maximized the reactivity of phospholipids hydrolysis with immobilized industrial-class phospholipase A1 (PLA1) at the desired water content in the water-in-oil (W/O) microemulsion phase. The optimal hydrophobic-hydrophilic condition of the reaction media in a hydrophobic enzyme reaction is critical to realize the maximum yields of enzyme activity of phospholipase A1. It was attributed to enzymes disliking hydrophobic surroundings as a special molecular structure for reactivity. Immobilization of PLA1 was successfully achieved with the aid of a hydrophobic carrier (Accurel MP100) combination with the treatment using glutaraldehyde. The immobilized yield was over 90% based on simple adsorption. The hydrolysis reaction was kinetically investigated through the effect of glutaraldehyde treatment of carrier and water content in the W/O microemulsion phase. The initial reaction rate increased linearly with an increasing glutaraldehyde concentration and then leveled off over a 6% glutaraldehyde concentration. The initial reaction rate, which was predominantly driven by the water content in the organic phase, changed according to a typical bell-shaped curve with respect to the molar ratio of water to phospholipid. It behaved in a similar way with different glutaraldehyde concentrations. After 10 cycles of repeated use, the reactivity was well sustained at 40% of the initial reaction rate and the creation of the final product. Accumulated yield after 10 times repetition was sufficient for industrial applications. Immobilized PLA1 has demonstrated potential as a biocatalyst for the production of phospholipid biochemicals.

Hydraulic segmentation does not protect stems from acute water loss during fire

2021 ◽  
Author(s):  
William A Hoffmann ◽  
Amanda C Rodrigues ◽  
Nicholas Uncles ◽  
Lorenzo Rossi
Keyword(s):  
Water Uptake ◽  
Water Loss ◽  
High Water ◽  
Fire Plume ◽  
Magnolia Grandiflora ◽  
Hydraulic Failure ◽  
Factors Influencing ◽  
Wide Range ◽  
Transport Path ◽  
Measured Water

Abstract The heat plume associated with fire has been hypothesized to cause sufficient water loss from trees to induce embolism and hydraulic failure. However, it is unclear whether the water transport path remains sufficiently intact during scorching or burning of foliage to sustain high water loss. We measured water uptake by branches of Magnolia grandiflora while exposing them to a range of fire intensities, and examined factors influencing continued water uptake after fire. Burning caused a 22-fold mean increase in water uptake, with greatest rates of water loss observed at burn intensities that caused complete consumption of leaves. Such rapid uptake is possible only with steep gradients in water potential, which would likely result in substantial cavitation of xylem and loss of conductivity in intact stems. Water uptake continued after burning was complete, and was greatest following burn intensities that killed leaves but did not consume them. This post-fire uptake was mostly driven by rehydration of the remaining tissues, rather than evaporation from the tissues. Our results indicate that the fire-plume hypothesis can be expanded to include a wide range of burning conditions experienced by plants. High rates of water loss are sustained during burning, even when leaves are killed or completely consumed.

SFM and TOF-SIMS Study of Novel Self-Organization phenomena in mixed LB monolayers

2002 ◽  
Vol 738 ◽  
Author(s):  
B. Pignataro ◽  
L. Sardone ◽  
A. Licciardello ◽  
G. Marletta
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Scanning Force Microscopy ◽  
Lateral Force ◽  
Self Organization ◽  
High Mass ◽  
Molar Ratio ◽  
Force Microscopy ◽  
Tof Sims ◽  
Wide Range ◽  
Scanning Force

ABSTRACTMixed monolayers of dimyristoylphosphatidylcholine (DMPC) and quercetin palmitate (QP) in a molar ratio of 25/75 have been transferred on mica and oxygen plasma cleaned silicon by the Langmuir-Blodgett (LB) technique at different subphase temperatures. Scanning Force Microscopy (SFM) in height, phase and lateral force modes has been employed to investigate the structural and mechanical features at nanoscopic level of these samples. Although the two molecules show a wide range of miscibility at 37 °C, they give rise to phase separation at 10 °C. This last system provides a new example of nanometric scale self-organization. In particular spiral shaped domains rising from the wrapping-up of nanoscopic fiber-like structures have been observed. The high resolution achieved by the use of the dynamic scanning force microscopy operating in the net attractive regime allow to visualize characteristic nanoscopic rupture points along the supramolecular fibers. High mass resolution Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) spectra showed DMPC- as well as QP-related peaks. The ToF-SIMS spectra from the nanostructured samples (10 °C) have been compared with those from the homogeneous ones (37 °C). The phase separated samples provides interesting secondary ions that highlight the QP supramolecular condensation within the fiber-like structures.

scholarly journals Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

2016 ◽  
Vol 12 ◽  
pp. 2627-2635 ◽  
Author(s):  
Federica Santoro ◽  
Matteo Mariani ◽  
Federica Zaccheria ◽  
Rinaldo Psaro ◽  
Nicoletta Ravasio
Keyword(s):  
Reaction Rate ◽  
Solid Acid ◽  
Amorphous Solid ◽  
Solid Acid Catalysts ◽  
Acid Catalysts ◽  
Alumina Catalyst ◽  
Reaction Conditions ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Silica Alumina

The synthesis of thioethers starting from alcohols and thiols in the presence of amorphous solid acid catalysts is reported. A silica alumina catalyst with a very low content in alumina gave excellent results in terms of both activity and selectivity also under solvent-free conditions. The reaction rate follows the electron density of the carbinol atom in the substrate alcohol and yields up to 99% and can be obtained for a wide range of substrates under mild reaction conditions.

The Control of the Reactions of Strontium Hexaferrite Formation by the Molar Ratio of Precursors

2007 ◽  
Vol 280-283 ◽  
pp. 471-472
Author(s):  
S.A. Seyyed Ebrahimi
Keyword(s):  
Critical Parameters ◽  
Molar Ratio ◽  
Strontium Hexaferrite ◽  
Strontium Oxide ◽  
Molar Ratios ◽  
Temperature Method ◽  
Wide Range ◽  
Method Of Production ◽  
Thermal Analysis Techniques

Strontium hexaferrite is one of the very important categories of magnetic materials with a wide range applications. One of the very critical parameters in the high temperature method of production of this material is molar ratio of iron oxide to strontium oxide. Although there could be found some reports on the effect of this parameter on the physical properties of the material in the literature but there are very few investigations about the role of this factor on the reactions occurred in the process. In this work the effect of different molar ratios of precursors on the reactions carried out for processing of strontium hexaferrite have been investigated by using thermal analysis techniques such as DTA/TG. Furthermore, the microstructure and the powder and bulk magnetic properties of the products have been studied by SEM, VSM and permeameter.

scholarly journals Reaction Rate Retardation as a Method for Serum Alkaline Phosphatase Isoenzyme Measurement

1980 ◽  
Vol 17 (4) ◽  
pp. 192-198 ◽  
Author(s):  
Pamela B Brown ◽  
K O Lewis
Keyword(s):  
Alkaline Phosphatase ◽  
Reaction Rate ◽  
Serum Alkaline Phosphatase ◽  
Enzyme Reaction ◽  
Intestinal Alkaline Phosphatase ◽  
Wide Range ◽  
Alkaline Phosphatase Isoenzymes ◽  
Sensitivity And Selectivity ◽  
Rate Retardation ◽  
Alkaline Phosphatase Isoenzyme

A method for serum alkaline phosphatase isoenzymes using an enzyme reaction rate analyser is described. The complete urea-induced degradation of enzyme activity is monitored, from which individual isoenzyme activities are obtained by calculating the constituent exponential components of the degradation curve. Activities have been measured with adequate sensitivity and selectivity for up to four isoenzyme components in normal and in pathological sera. The identity of each isoenzyme present is assigned from its characteristic degradation half-life, and by this method bone and liver alkaline phosphatase are clearly distinguished and quantitated, and a composite value for placental-intestinal alkaline phosphatase activity is obtained. The approach promises to be applicable to a wide range of isoenzymes, and in analogy with ‘reaction rate’ the term ‘reaction rate retardation’ is suggested for the procedure.

scholarly journals A systematic review of provider-and system-level factors influencing the delivery of cardiac rehabilitation for heart failure

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Paulina Daw ◽  
Thomas M. Withers ◽  
Jet J. C. S. Veldhuijzen van Zanten ◽  
Alexander Harrison ◽  
Colin J. Greaves
Keyword(s):  
Heart Failure ◽  
Systematic Review ◽  
Cardiac Rehabilitation ◽  
Thematic Analysis ◽  
System Level ◽  
Future Research ◽  
Heart Failure Patients ◽  
Barriers And Enablers ◽  
Factors Influencing ◽  
Wide Range

Abstract Background There is a longstanding research-to-practice gap in the delivery of cardiac rehabilitation for patients with heart failure. Despite adequate evidence confirming that comprehensive cardiac rehabilitation can improve quality of life and decrease morbidity and mortality in heart failure patients, only a fraction of eligible patients receives it. Many studies and reviews have identified patient-level barriers that might contribute to this disparity, yet little is known about provider- and system-level influences. Methods A systematic review using narrative synthesis. The aims of the systematic review were to a) determine provider- and system-level barriers and enablers that affect the delivery of cardiac rehabilitation for heart failure and b) juxtapose identified barriers with possible solutions reported in the literature. A comprehensive search strategy was applied to the MEDLINE, Embase, PsycINFO, CINAHL Plus, EThoS and ProQuest databases. Articles were included if they were empirical, peer-reviewed, conducted in any setting, using any study design and describing factors influencing the delivery of cardiac rehabilitation for heart failure patients. Data were synthesised using inductive thematic analysis and a triangulation protocol to identify convergence/contradiction between different data sources. Results Seven eligible studies were identified. Thematic analysis identified nine overarching categories of barriers and enablers which were classified into 24 and 26 themes respectively. The most prevalent categories were ‘the organisation of healthcare system’, ‘the organisation of cardiac rehabilitation programmes’, ‘healthcare professional’ factors and ‘guidelines’. The most frequent themes included ‘lack of resources: time, staff, facilities and equipment’ and ‘professional’s knowledge, awareness and attitude’. Conclusions Our systematic review identified a wide range of provider- and system-level barriers impacting the delivery of cardiac rehabilitation for heart failure, along with a range of potential solutions. This information may be useful for healthcare professionals to deliver, plan or commission cardiac rehabilitation services, as well as future research.

scholarly journals Sol-Gel Immobilisation of Lipases: Towards Active and Stable Biocatalysts for the Esterification of Valeric Acid

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2283 ◽  
Author(s):  
Soledad Cebrián-García ◽  
Alina Balu ◽  
Araceli García ◽  
Rafael Luque
Keyword(s):  
Microwave Irradiation ◽  
Sol Gel ◽  
Valeric Acid ◽  
Added Value ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Highly Active ◽  
Industrial Sectors ◽  
Wide Range ◽  
Acid Esterification

Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of valeric acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80–85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of valeric acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.

Contextual Influences on Science Teachers' TPACK Levels

2015 ◽  
pp. 307-333 ◽  
Author(s):  
Kofi Acheaw Owusu ◽  
Lindsey Conner ◽  
Chris Astall
Keyword(s):  
Case Studies ◽  
Science Teachers ◽  
Teaching And Learning ◽  
Contextual Influences ◽  
Learning Context ◽  
Pedagogical Content ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Wide Range ◽  
Technology In Instruction

The contextual factors influencing teachers' use of technology as well as teachers' Technological Pedagogical Content Knowledge (TPACK) levels were investigated through multiple embedded case studies of five science teachers who were regular users of technology in their teaching. The case studies reported in this chapter revealed that teachers used technology to support inquiry learning through a wide range of ways in lower levels of high school but mostly to clarify concepts and theories for senior level students. This chapter identified that teachers demonstrated different TPACK levels of expertise and engagement in the use of technology when transferring different types of knowledge from one teaching and learning context to another and for addressing differences amongst learners. The context of assessment driven teaching influences science teachers' TPACK for integrating technology in instruction. The chapter noted that having teachers actively evaluate the effectiveness of the technology on students' learning may help increase teachers' TPACK levels.

Contextual Influences on Science Teachers' TPACK Levels

2018 ◽  
pp. 448-475
Author(s):  
Kofi Acheaw Owusu ◽  
Lindsey Conner ◽  
Chris Astall
Keyword(s):  
Case Studies ◽  
Science Teachers ◽  
Teaching And Learning ◽  
Contextual Influences ◽  
Learning Context ◽  
Pedagogical Content ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Wide Range ◽  
Technology In Instruction

The contextual factors influencing teachers' use of technology as well as teachers' Technological Pedagogical Content Knowledge (TPACK) levels were investigated through multiple embedded case studies of five science teachers who were regular users of technology in their teaching. The case studies reported in this chapter revealed that teachers used technology to support inquiry learning through a wide range of ways in lower levels of high school but mostly to clarify concepts and theories for senior level students. This chapter identified that teachers demonstrated different TPACK levels of expertise and engagement in the use of technology when transferring different types of knowledge from one teaching and learning context to another and for addressing differences amongst learners. The context of assessment driven teaching influences science teachers' TPACK for integrating technology in instruction. The chapter noted that having teachers actively evaluate the effectiveness of the technology on students' learning may help increase teachers' TPACK levels.

Sign in / Sign up

Export Citation Format

Share Document