scholarly journals Preparation and properties of nanoparticles by chemical reactions with assistance of physics factors

2013 ◽  
Vol 16 (1) ◽  
pp. 86-91
Author(s):  
Hai Hoang Nguyen ◽  
Phu Dang Nguyen ◽  
Tuan Quoc Tran ◽  
Luong Hoang Nguyen
Keyword(s):  
Elevated Temperature ◽  
Chemical Reactions ◽  
High Surface ◽  
High Surface Area ◽  
Physical Factors ◽  
Fast Heating ◽  
Preparation Methods ◽  
Iron Platinum ◽  
Ultra Fast Cooling ◽  
Temperature And Pressure

Versatile chemical reactions with the help of physical factors such as microwaves, sonic radiations, laser, elevated temperature and pressure have successfully been used to prepared silicon (high surface area), iron oxide (in amorphous and crystalline state), silver, gold, iron-platinum, cobalt-platinum nanoparticles. The microwaves fostered the chemical reactions via homogeneous and fast heating processes; the sonic radiations from an ultrasonicator created ultra-fast cooling rates at high power or just played a role of mechanical waves at low power; laser provided energy nanoparticles from bulk plates; elevated temperature and pressure produced good environments for unique reactions. All those preparation methods are simple and inexpensive but they could produce nanoparticles with interesting properties.

scholarly journals Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 426
Author(s):  
Vaibhav Kumar Maurya ◽  
Amita Shakya ◽  
Manjeet Aggarwal ◽  
Kodiveri Muthukaliannan Gothandam ◽  
Torsten Bohn ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Research Area ◽  
Delivery Systems ◽  
Preparation Methods ◽  
Bioactive Agents ◽  
Unique Composition ◽  
Targeted Release ◽  
Β Carotene ◽  
Regulatory Challenges

Nanotechnology has opened new opportunities for delivering bioactive agents. Their physiochemical characteristics, i.e., small size, high surface area, unique composition, biocompatibility and biodegradability, make these nanomaterials an attractive tool for β-carotene delivery. Delivering β-carotene through nanoparticles does not only improve its bioavailability/bioaccumulation in target tissues, but also lessens its sensitivity against environmental factors during processing. Regardless of these benefits, nanocarriers have some limitations, such as variations in sensory quality, modification of the food matrix, increasing costs, as well as limited consumer acceptance and regulatory challenges. This research area has rapidly evolved, with a plethora of innovative nanoengineered materials now being in use, including micelles, nano/microemulsions, liposomes, niosomes, solidlipid nanoparticles, nanostructured lipids and nanostructured carriers. These nanodelivery systems make conventional delivery systems appear archaic and promise better solubilization, protection during processing, improved shelf-life, higher bioavailability as well as controlled and targeted release. This review provides information on the state of knowledge on β-carotene nanodelivery systems adopted for developing functional foods, depicting their classifications, compositions, preparation methods, challenges, release and absorption of β-carotene in the gastrointestinal tract (GIT) and possible risks and future prospects.

Preparation of Highly Crystalline Mesoporous TiO2 by Using Carbon to Protect the Pore Structure at Elevated Temperature

2010 ◽  
Vol 654-656 ◽  
pp. 2406-2409
Author(s):  
Yu Dan Zhu ◽  
Yu Lan Ding ◽  
Xiao Hua Lu ◽  
Wei Zhuang ◽  
Ling Hong Lu
Keyword(s):  
Elevated Temperature ◽  
Pore Structure ◽  
Anatase Phase ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Pore Wall ◽  
Mesoporous Tio2 ◽  
Mesopore Structure ◽  
Novel Strategy

Mesoporous TiO2 with highly crystalline pore wall has an enormous potential for applications in photocatalysis, catalyst support, drug delivery, etc. However, with the sintering temperature increasing, the crystallinity of the pore wall increases while the mesopore structure tends to collapse. In this work, we presented a novel strategy for creating highly crystalline mesoporous TiO2 (MT800) by using carbon to protect the pore structure at elevated temperature. The structural characterization indicates that MT800 has highly crystalline anatase phase and processes high surface area. The photocatalysis performance was evaluated by organic degradation and the results show that MT800 has superior photocatalysis activity to the TiO2 (T800) calcined at 800°C without carbon, because of the synergies of crystallinity and mesostructure.

scholarly journals ZIF-8 Metal Organic Framework for the Conversion of Glucose to Fructose and 5-Hydroxymethyl Furfural

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 812 ◽  
Author(s):  
Ryan Oozeerally ◽  
Shivendra D. K. Ramkhelawan ◽  
David L. Burnett ◽  
Christiaan H. L. Tempelman ◽  
Volkan Degirmenci
Keyword(s):  
Hydrothermal Synthesis ◽  
Flow Reactor ◽  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Synthesis Method ◽  
Reaction Medium ◽  
Zeolitic Imidazolate Framework ◽  
Preparation Methods ◽  
Hydroxymethyl Furfural

Herein, Zeolitic imidazolate framework-8 (ZIF-8) is considered as an easy and cheap to prepare alternative catalyst for the isomerization of glucose and production of 5-hydroxymethyl furfural (HMF). For the synthesis of the ZIF-8 catalysts two preparation methods were evaluated, being room temperature and hydrothermal synthesis at 140 °C. Of these, the hydrothermal synthesis method yields a material with exceptionally high surface area (1967 m2·g−1). As a catalyst, the ZIF-8 materials generated excellent fructose yields. Specifically, ZIF-8 prepared by hydrothermal synthesis yielded a fructose selectivity of 65% with a glucose conversion of 24% at 100 °C in aqueous reaction medium. However, this selectivity dropped dramatically when the reactions were repeated at higher temperatures (~140 °C). Interestingly, greater quantities of mannose were produced at higher temperatures too. The lack of strong Brønsted acidity in both ZIF-8 materials resulted in poor HMF yields. In order to improve HMF yields, reactions were performed at a lower pH of 1.0. At 140 °C the lower pH was found to drive the reaction towards HMF and double its yield. Despite the excellent performance of ZIF-8 catalysts in batch reactions, their activity did not translate well to the flow reactor over a continuous run of 8 h, which was operating with a residence time of 6 min. The activity of ZIF-8 halved in the flow reactor at 100 °C in ~3 h, which implies that the catalyst’s stability was not maintained in the long run.

scholarly journals Preparation and Characterization of NiMo/Al2O3Catalyst for Hydrocracking Processing

2018 ◽  
Vol 31 ◽  
pp. 03011
Author(s):  
Aditya Widiyadi ◽  
Gema Adil Guspiani ◽  
Jeffry Riady ◽  
Rikky Andreanto ◽  
Safina Dea Chaiunnisa ◽  
...  
Keyword(s):  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Potassium Sulfate ◽  
Impregnation Method ◽  
Active Components ◽  
Hydrocracking Process ◽  
Hydrocracking Catalyst ◽  
Temperature And Pressure ◽  
Petroleum Refineries

Hydrocracking is a chemical process used in petroleum refineries for converting high boiling hydrocarbons in petroleum crude oils to more valuable lower boiling products such as gasoline, kerosene, and diesel oil that operate at high temperature and pressure. Catalyst was used in hydrocracking to reduce temperature and pressure. Hydrocracking catalyst are composed of active components and support. Alumina is widely used in hydrocracking process as catalyst support due to its high surface area, high thermal stability, and low prices. The objective of this research was preparated NiMo/Al2O3 catalyst that used as hydrocracking catalyst. Catalyst was synthesized by wetness impregnation method and simple heating method with various kind of Al2O3. The physicochemical properties of catalyst were investigated by X-ray diffraction (XRD) to determine type of crystal and scanning electron microscopy (SEM) to determine morphology of the catalyst. The NiMo/Al2O3 catalyst prepared by aluminium potassium sulfate dodecahydrate exhibited the highest crystallinity of 90.23% and it is clear that MoO3 and NiO crystallites are highly dispersed on the NiMo/Al2O3 catalyst which indicates as the best catalyst. The catalytic activity in hydrocracking process was successfully examined to convert fatty acid into hydrocarbon.

scholarly journals Compositing Two-Dimensional Materials with TiO2 for Photocatalysis

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 590 ◽  
Author(s):  
Yu Ren ◽  
Yuze Dong ◽  
Yaqing Feng ◽  
Jialiang Xu
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Clean Energy ◽  
Two Dimensional ◽  
Preparation Methods ◽  
2D Material ◽  
Carrier Recombination ◽  
Two Dimensional Materials ◽  
Physical And Chemical

Energy shortage and environmental pollution problems boost in recent years. Photocatalytic technology is one of the most effective ways to produce clean energy—hydrogen and degrade pollutants under moderate conditions and thus attracts considerable attentions. TiO2 is considered one of the best photocatalysts because of its well-behaved photo-corrosion resistance and catalytic activity. However, the traditional TiO2 photocatalyst suffers from limitations of ineffective use of sunlight and rapid carrier recombination rate, which severely suppress its applications in photocatalysis. Surface modification and hybridization of TiO2 has been developed as an effective method to improve its photocatalysis activity. Due to superior physical and chemical properties such as high surface area, suitable bandgap, structural stability and high charge mobility, two-dimensional (2D) material is an ideal modifier composited with TiO2 to achieve enhanced photocatalysis process. In this review, we summarized the preparation methods of 2D material/TiO2 hybrid and drilled down into the role of 2D materials in photocatalysis activities.

Physicochemical, catalytic, and antimicrobial activities of porous cobalt oxide nanoparticles (kinetics study of H2O2 decomposition using fluorometric and gasometric methods)

2018 ◽  
Vol 96 (8) ◽  
pp. 828-834 ◽  
Author(s):  
Marwa M. Ibrahim ◽  
Sahar A. El-Molla
Keyword(s):  
Antimicrobial Activity ◽  
Catalytic Activity ◽  
Hydrothermal Method ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Efficiency ◽  
Antimicrobial Activities ◽  
Preparation Methods ◽  
Cobalt Oxide Nanoparticles ◽  
H2o2 Decomposition

Co3O4 nanomaterials were prepared by different methods. The samples were nominated as Co3O4 (Pr), Co3O4 (Co), and Co3O4 (Hy) due to preparation by precipitation, combustion, and a hydrothermal method, respectively. These nanomaterials were characterized by studying their structural, morphological, and surface properties. The catalytic activity was evaluated by following H2O2 decomposition through fluorometric and gasometric methods. The obtained results showed that the catalytic efficiency of the catalysts was affected by their preparation methods. The order of catalytic activities of the investigated samples using fluorometric method is compatible with that obtained by gasometric method. Co3O4 (Hy) exhibited much higher catalytic activity due to the high surface area, small particle size, different oxidation states, different shapes, and the high production of hydroxyl radical. The antimicrobial activity is studied against standard bacterial and fungal strains, and the studies showed that the hydrothermal method enhanced antimicrobial activity more than other preparation methods.

Metal-organic framework-derived structures for next-generation rechargeable batteries

2018 ◽  
Vol 11 (06) ◽  
pp. 1830006 ◽  
Author(s):  
Wenhui Shi ◽  
Xilian Xu ◽  
Lin Zhang ◽  
Wenxian Liu ◽  
Xiehong Cao
Keyword(s):  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Lithium Ion ◽  
Rechargeable Batteries ◽  
Next Generation ◽  
Design Strategies ◽  
Energy Storage Devices ◽  
Preparation Methods ◽  
Metal Organic

Metal-organic frameworks (MOFs) have attracted great attention as versatile precursors or sacrificial templates for the preparation of novel porous structures. Due to their tunable compositions, structures and porosities as well as high surface area, MOF-derived materials have revealed promising performance for energy storage devices. In this mini review, the recent progress of MOF-derived materials as electrodes of next-generation rechargeable batteries was summarized. We briefly introduce the preparation methods, various design strategies and the structure-dependent performance of recently reported MOF-derived materials as electrodes of post-lithium-ion batteries, focusing on lithium-sulfur (Li-S) batteries, sodium-ion batteries (SIBs) and metal–air batteries. Finally, we give the conclusion with some insights into future development of MOF-derived materials for next-generation rechargeable batteries.

scholarly journals Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

2021 ◽  
Author(s):  
Vaibhav Maurya ◽  
Amita Shakya ◽  
Manjeet Aggarwal ◽  
K.M. Gothandam ◽  
Torsten Bohn ◽  
...  
Keyword(s):  
Oral Delivery ◽  
Water Solubility ◽  
High Surface ◽  
High Surface Area ◽  
Research Area ◽  
Delivery Systems ◽  
Preparation Methods ◽  
Bioactive Agents ◽  
Unique Composition ◽  
Β Carotene

Accruing evidence on the influence of β-carotene regarding the prevention of several chronic diseases - in addition to its well-acknowledged role in vision has been a strong driver for developing alternative delivery systems. Though oral delivery is accepted as the most fitting, mild and safe path for delivering bioactive agents, β-carotene delivery via food items poses challenges due to its lipophilic nature, poor water-solubility, high chemical/photochemical instability and poor oral bioavailability. Nanotechnology has opened new windows for delivering bioactive agents. Their physiochemical characteristics, i.e. small size, high surface area, unique composition, biocompatibility and biodegradability make these nanomaterials an attractive tool for β-carotene delivery. Delivering β-carotene through nanoparticles does not only improve its bioavailability/bioaccumulation in target tissues, but also lessens its sensitivity against environmental factors during processing. Regardless of these benefits, nanocarriers inherit some limitations, such as variations in sensory quality, modification of the food matrix, increasing costs, as well as limited consumer acceptance and regulatory challenges. This research area has been rapidly evolved, with a plethora of innovative nano-engineered materials, including micelles, nano/microemulsion, liposomes, niosomes, solid-lipid nanoparticles and nanostructured lipid carriers. These nano-delivery systems make conventional delivery systems appear archaic and promise better solubilization, protection during processing, improved shelf-life, higher bioavailability as well as controlled and targeted release. This review provides information on the state of knowledge on β-carotene nano-delivery systems adopted for developing functional foods: depicting their classification, composition, preparation methods, challenges, release-and absorption of β-carotene in the GIT and possible risks and future prospects.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

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