scholarly journals Gas-Phase Synthesis of Functional Nanomaterials

Applied Nano ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 25-58
Author(s):  
Vladimir N. Popok ◽  
Ondřej Kylián
Keyword(s):  
Gas Phase ◽  
Composite Films ◽  
Chemical Properties ◽  
Industrial Applications ◽  
Cluster Beam ◽  
Soft Landing ◽  
Current State ◽  
History Of ◽  
Pros And Cons ◽  
Physical And Chemical

Nanoparticles (NPs) of different types, especially those of metals and metal oxides, are widely used in research and industry for a variety of applications utilising their unique physical and chemical properties. In this article, the focus is put on the fabrication of nanomaterials by means of gas-phase aggregation, also known as the cluster beam technique. A short overview of the history of cluster sources development emphasising the main milestones is presented followed by the description of different regimes of cluster-surface interaction, namely, soft-landing, pinning, sputtering and implantation. The key phenomena and effects for every regime are discussed. The review is continued by the sections describing applications of nanomaterials produced by gas aggregation. These parts critically analyse the pros and cons of the cluster beam approach for catalysis, formation of ferromagnetic and superparamagnetic NPs, applications in sensor and detection technologies as well as the synthesis of coatings and composite films containing NPs in research and industrial applications covering a number of different areas, such as electronics, tribology, biology and medicine. At the end, the current state of the knowledge on the synthesis of nanomaterials using gas aggregation is summarised and the strategies towards industrial applications are outlined.

Micro-Ribbons and Micro-Wires Silica Synthesis Using Bottom-Top Technique

2020 ◽  
Vol 1008 ◽  
pp. 33-38
Author(s):  
Marwa Nabil ◽  
Hussien A. Motaweh
Keyword(s):  
Selection Process ◽  
Chemical Properties ◽  
Industrial Applications ◽  
Preparation Process ◽  
Pure Silica ◽  
One Step ◽  
Materials Used ◽  
Sonication Technique ◽  
Silica Synthesis ◽  
Physical And Chemical

Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation mechanism is the sonication time of silica powder production during the dual technique. The product stages are as follows; silica nanoparticles (21-38 nm), nanoclusters silica (46 – 67 nm), micro-wires silica (1.17 – 6.29 μm), and micro-ribbons silica (19.4 – 54.1 μm). It's allowing for use in environmental applications (multiple wastewater purification, multiple uses in air filters, as well as many industrial applications).

Di-imide: Some Physical and Chemical Properties, and the Kinetics and Stoichiometry of the Gas-phase Decomposition

1973 ◽  
Vol 51 (21) ◽  
pp. 3605-3619 ◽  
Author(s):  
C. Willis ◽  
R. A. Back
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Chemical Properties ◽  
Phase Decomposition ◽  
Important Intermediate ◽  
Long Lifetime ◽  
Physical And Chemical ◽  
Text Formation ◽  
Kinetics Of

Preparation of di-imide by passing hydrazine vapor through a microwave discharge yields mixtures with NH3 containing typically about 15% N2H2, estimated from the gases evolved on decomposition. The behavior of the mixture (which melts at −65 °C) on warming from −196 to −30 °C suggests a strong interaction between the components. Measurements of magnetic susceptibility and e.p.r. experiments showed that N2H2 is not strongly paramagnetic, which with other observations points to a singlet rather than a triplet ground-state.Di-imide can be vaporized efficiently, together with NH3, by rapid warming, and the vapor is surprisingly long-lived, with a typical half-life of several minutes at room temperature. The near-u.v. (3200–4400 Å) absorption spectrum of the vapor was photographed; it shows well-defined but diffuse bands, with εmax = 6(± 3) at 3450 Å.Di-imide decomposes at room temperature in two ways:[Formula: see text][Formula: see text]Formation of NH3 was not observed but cannot be ruled out. The decomposition of the vapor is complicated by a sizeable and variable decomposition that occurs rapidly during the vaporization. The stoichiometry of this and the vapor-phase decomposition depends on total pressure and di-imide concentration. The kinetics of the decomposition of the vapor were studied from 22 to 200 °C by following the disappearance of N2H2 by absorption of light at 3450 Å, or the formation of N2H4 by absorption at 2400 Å, and by mass spectrometry. The kinetics are complex and can be either first- or second-order, or mixed, depending on surface conditions. The effect of olefin additives on the decomposition was studied, and is also complex.Mechanisms for the decomposition are discussed, including the possible role of trans-cis isomerization. The relatively long lifetime found for di-imide in the gas phase suggests that it may be an important intermediate in many reactions of hydronitrogen systems.

scholarly journals Database indexing: yesterday and today

2004 ◽  
Vol 24 (2) ◽  
pp. 85-95
Author(s):  
Harry Diakoff
Keyword(s):  
Future Prospects ◽  
Current State ◽  
Database Indexing ◽  
History Of ◽  
Pros And Cons

This article surveys the history of database indexing and considers its current state and future prospects. It reviews the pros and cons of computerized searching, the rise and fall (and possible rise again) of private databases, and methods of framing and normalizing queries.

scholarly journals Synthesis and thermal properties of some phenolic resins

2019 ◽  
Vol 7 (1) ◽  
pp. 1-15
Author(s):  
Alshawi F M ◽  
Abdul Razzq K ◽  
Hanoosh W S
Keyword(s):  
Phenol Formaldehyde ◽  
Chemical Properties ◽  
Decomposition Temperature ◽  
Industrial Applications ◽  
Stability Study ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Physical And Chemical

Introduction: Phenolic resins have been in use since the early twentieth century and are considered the first class of synthetic polymers to achieve commercial success, moreover phenolic resins continue to succeed and attract special interest in a large range of industrial applications such as adhesives, paints, and composites; because of their unique physical and chemical properties. Materials and Methods: Prepolymers resol resins (RR, RH, RP, and RC) were synthesized by the reaction of phenolic compounds (resorcinol, hydroquinone, phloroglucinol, and catechol) respectively, with formaldehyde at molar ratio phenol/ formaldehyde 1/1.5, using sodium hydroxide as a catalyst. These resins were characterized by FTIR. The curing reaction of these resins was evaluated using differential scanning calorimetry (DSC), while the thermal stability study was evaluated using thermogravimetric analysis (TGA). Results and Discussion:From the results showing that these prepolymers have different curing temperatures and curing energy, while the TGA study showed that the cured resins have decomposition temperature more than 300 ºC, and char residue at 650 ºC more than 60%. Conclusions: These resol resins have different gel times (8-55) min, and viscosities (435-350) mpa.s. The curing temperature of these resin obtained from DSC curves was (120, 129, 105 and 127 °C), while the thermal behavior of the cured resins obtained from TGA curves showed that these cured resin have two decomposition temperatures and the rate of decomposition in the order of RC < RR< .

PROPERTIES AND EFFECTS OF NONPETROLEUM OILS

1975 ◽  
Vol 1975 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Hans J. Crump-Wiesner ◽  
Allen L. Jennings
Keyword(s):  
Pollution Control ◽  
Environmental Protection Agency ◽  
Oil Spills ◽  
Chemical Properties ◽  
Protection Agency ◽  
Legislative History ◽  
History Of ◽  
Physical And Chemical ◽  
Petroleum Oil ◽  
And Chemical Properties

ABSTRACT Legislative history of water pollution control has not included detailed scientific definitions of what is meant by the rather inclusive term “oil.” Because of the publicity surrounding spills of crude or petroleum-derived oils, little attention has been focused on non-petroleum oils. Approximately 5% of the oil spills reported to the Environmental Protection Agency are nonpetroleum oils. Their physical and chemical properties and adverse environmental effects are strikingly similar to the behavior of petroleum oil in the aquatic environment. This paper presents a comparative analysis of the properties and effects of petroleum versus nonpetroleum oils. Their similarities prove that these oils should be treated as one entity regardless of their origin. Finally, additional guidelines are presented to provide a more broadly applicable distinction between oil and other hazardous materials for enforcement purposes.

scholarly journals Characterizations and Application of Supported Ionic Liquid [bmim][CF3SO3]/SiO2 in CO2 Capture

2017 ◽  
Vol 888 ◽  
pp. 485-490
Author(s):  
Tengku Sharifah Marliza ◽  
Mohd Ambar Yarmo ◽  
Azizul Hakim ◽  
Maratun Najiha Abu Tahari ◽  
Yun Hin Taufiq-Yap
Keyword(s):  
Ionic Liquid ◽  
Atmospheric Pressure ◽  
Gas Adsorption ◽  
Chemical Properties ◽  
Industrial Applications ◽  
Supported Ionic Liquid ◽  
Adsorption Of Co ◽  
Adsorption Desorption ◽  
Physical And Chemical ◽  
And Chemical Properties

Supported ionic liquid (IL) [bmim][CF3SO3] on SiO2 was prepared, characterized and its potential evaluated for CO2 capture via adsorption and desorption studies using gas adsorption analyzer. The physical and chemical properties were determined using N2 adsorption/desorption and CO2-TPD analysis. The increasing IL loading caused a drastic decrease in the surface area as well as pore volume due to the confinement of IL within the micropore and mesopore area. However, the increasing IL loading increased the basicity of the sorbent which significantly enhanced CO2 chemisorption. Supported [bmim][CF3SO3] on SiO2 revealed the physical and chemical adsorption of CO2 and resulted in a remarkable CO2 adsorption capacity at atmospheric pressure and room temperature (66.7 mg CO2/gadsorbent) which has great potential in industrial applications.

scholarly journals On the Violence of High Explosive Reactions

2005 ◽  
Vol 127 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Craig M. Tarver ◽  
Steven K. Chidester
Keyword(s):  
High Explosive ◽  
Chemical Properties ◽  
Subsequent Reaction ◽  
Energy Delivery ◽  
Current State ◽  
Slow Combustion ◽  
Shear Heating ◽  
Deposition Processes ◽  
Physical And Chemical ◽  
And Chemical Properties

High explosive reactions can be caused by three general energy deposition processes: impact ignition by frictional and/or shear heating; bulk thermal heating; and shock compression. The violence of the subsequent reaction varies from benign slow combustion to catastrophic detonation of the entire charge. The degree of violence depends on many variables, including the rate of energy delivery, the physical and chemical properties of the explosive, and the strength of the confinement surrounding the explosive charge. The current state of experimental and computer-modeling research on the violence of impact, thermal, and shock-induced reactions is briefly reviewed in this paper.

scholarly journals Critical assessment of the current state of scientific knowledge, terminology, and research needs concerning the role of organic aerosols in the atmosphere, climate, and global change

2006 ◽  
Vol 6 (7) ◽  
pp. 2017-2038 ◽  
Author(s):  
S. Fuzzi ◽  
M. O. Andreae ◽  
B. J. Huebert ◽  
M. Kulmala ◽  
T. C. Bond ◽  
...  
Keyword(s):  
Organic Aerosols ◽  
Chemical Properties ◽  
Research Priorities ◽  
Future Research ◽  
Current State ◽  
Basic Set ◽  
Physical And Chemical ◽  
Present Understanding ◽  
Key Questions

Abstract. In spite of impressive advances in recent years, our present understanding of organic aerosol (OA) composition, physical and chemical properties, sources and transformation characteristics is still rather limited, and their environmental effects remain highly uncertain. This paper discusses and prioritizes issues related to organic aerosols and their effects on atmospheric processes and climate, providing a basis for future activities in the field. Four main topical areas are addressed: i) sources of OA; ii) formation transformation and removal of OA; iii) physical, chemical and mixing state of OA; iv) atmospheric modelling of OA. Key questions and research priorities regarding these four areas are synthesized in this paper, and outstanding issues for future research are presented for each topical area. In addition, an effort is made to formulate a basic set of consistent and universally applicable terms and definitions for coherent description of atmospheric OA across different scales and disciplines.

scholarly journals Evidence for a New Plasma Thromboplastin Factor I. Case Report, Coagulation Studies and Physicochemical Properties

Blood ◽  
1965 ◽  
Vol 26 (5) ◽  
pp. 521-532 ◽  
Author(s):  
WILLIAM E. HATHAWAY ◽  
LORETTA P. BELHASEN ◽  
HELEN S. HATHAWAY
Keyword(s):  
Chemical Properties ◽  
Coagulation Factor ◽  
Factor Deficiency ◽  
Coagulation Factor Deficiency ◽  
History Of ◽  
Fresh Plasma ◽  
Physical And Chemical ◽  
Thromboplastin Factor ◽  
Antihemophilic Factor

Abstract Studies of defective plasma thromboplastin formation in four siblings indicated a defect which was different from any of the known coagulation factor deficiency states. Although none of the children had any history of hemorrhagic tendencies, a prolonged whole blood clotting time in an 11-year-old girl led to the findings of a markedly prolonged partial thromboplastin time (PTT), abnormal thromboplastin generation test (TGT), and a normal prothrombin time in the patient and in three of her ten siblings. The abnormal PTT and TGT were corrected by aluminum hydroxide adsorbed fresh plasma and by serum. Using the kaolin-PTT system, equal mixtures of plasma from the patients and normal plasma produced a normal time. In addition, plasmas deficient in plasma thromboplastin antecedent (PTA), Hageman factor (HF), antihemophilic factor (AHF), or plasma thromboplastin component (PTC) corrected the abnormality. Physical and chemical properties of plasma correcting the defect in vitro indicated that the defect is closely related to that found in PTA and HF deficient plasma.

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