scholarly journals Comparative Catalytic Evaluation of Nano-ZrOx Promoted Manganese Catalysts: Kinetic Study and the Effect of Dopant on the Aerobic Oxidation of Secondary Alcohols

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Mohamed E. Assal ◽  
Mufsir Kuniyil ◽  
Mujeeb Khan ◽  
Mohammed Rafi Shaik ◽  
Abdulrahman Al-Warthan ◽  
...  
Keyword(s):  
Reaction Time ◽  
Specific Activity ◽  
Aerobic Oxidation ◽  
Chemical Properties ◽  
High Specific Activity ◽  
Catalytic Efficiency ◽  
Manganese Carbonate ◽  
Spectroscopic Techniques ◽  
Oxidation Of Alcohols ◽  
Physical And Chemical

This work reports the zirconia (ZrOx) nanoparticles doped MnCO3 catalysts prepared by facile and simple coprecipitation technique and the synthesis of zirconia-manganese carbonate [X% ZrOx–MnCO3] (where X% = 0–7%) catalyst which upon calcination at 400°C is converted to zirconia-manganese dioxide [1% ZrOx–MnO2] and when calcined at 500°C is converted to zirconia-manganic trioxide [1% ZrOx–Mn2O3]. A comparative catalytic study was performed to investigate the catalytic efficiency between carbonate and oxides for the selective oxidation of 1-phenylethanol by using molecular O2 as a clean oxidant. The influence of several parameters such as w/w% of ZrOx, reaction time, calcination temperature, catalyst amount, and reaction temperature has been thoroughly examined using oxidation of 1-phenylethanol as a model substrate. The 1% ZrOx–MnCO3 precalcined at 300°C exhibited the best catalytic efficiency. It was found that ZrOx nanoparticles also play an essential role in enhancing the effectiveness of the catalytic system for the aerobic oxidation of alcohols. Furthermore, the physical and chemical properties of synthesized catalysts were evaluated by microscopic and spectroscopic techniques. An extremely high specific activity of 40 mmol·g−1·h−1 with a 100% conversion of oxidation product and selectivity of >99% was achieved within extremely short reaction time (6 min).

Computer Simulation of Grain Growth in Polycrystalline Aggregates

1982 ◽  
Vol 21 ◽  
Author(s):  
M. P. Anderson ◽  
D. J. Srolovitz ◽  
G. S. Grest ◽  
P. S. Sahni
Keyword(s):  
Grain Growth ◽  
Chemical Properties ◽  
Predictive Ability ◽  
Grain Morphology ◽  
Catalytic Efficiency ◽  
Second Phase ◽  
Controllable Factors ◽  
Polycrystalline Aggregates ◽  
Grain Growth Kinetics ◽  
Physical And Chemical

The physical and chemical properties of materials are determined in part by microstructure. Grain orientation and size in polycrystalline aggregates affect, for example, yield strength, catalytic efficiency, chemisorption, physisorption, fracture and a host of other properties. The final grain morphology is often determined by thermal processing, addition of a second phase, deformation, etc. However, in order to effectively tailor the microstructure for specific applications, the mechanism and kinetics of grain growth must be known. Unfortunately, present theories predict grain growth kinetics (1–3) which often differ from experimental observation, have little predictive ability with respect to microstructure and are not easily generalized to account for experimentally controllable factors.

Comparative Study of Two Blue Pigments from the Maya Region of Yucatan

2012 ◽  
Vol 1374 ◽  
pp. 115-123
Author(s):  
Silvia Fernández-Sabido ◽  
Yoly Palomo-Carrillo ◽  
Rafael Burgos-Villanueva ◽  
Romeo de Coss
Keyword(s):  
Comparative Study ◽  
Chemical Properties ◽  
Eighth Century ◽  
Blue Pigment ◽  
Spectroscopic Techniques ◽  
Two Samples ◽  
Traditional Preparation ◽  
Maya Blue ◽  
Maya People ◽  
Physical And Chemical

ABSTRACTA comparative study of two blue pigment found in separate megalithic structures in Yucatán México is presented. The first sample (M1) is a piece of turquoise stucco discovered at the top of a building known as Structure-2 in the town of Dzilam González. The second sample (M2) is a residual blue powder that was contained in a Oxcum Café type ceramic vessel recovered in the rubble of the Kabul building in Izamal city. The interest in characterizing these samples increases with the possibility of finding in them evidence of Maya Blue, a dye created in the eighth century by the Maya people, whose extraordinary physical and chemical properties have been studied in laboratories around the world. Maya Blue was a tailored technology used for several centuries, even during the Spanish occupation, throughout Mesoamerica. Despite 80 years of study, the mysteries of its composition, traditional preparation and obsolescence have not yet been fully resolved. Using different spectroscopic techniques (SEM, EDX, XRD, FTIR, UV-Vis DR) we have studied and compared the blue colorants in M1 and M2. Results indicate that M1 is Maya Blue. Despite some similarities in the infrarred vibrational spectra of the two samples, we have determinated that M2 is not Maya Blue but a non-Mesoamerican mineral pigment known as Ultramarine which was probably introduced to America by Europeans.

scholarly journals Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability

2015 ◽  
Vol 6 ◽  
pp. 2263-2271 ◽  
Author(s):  
Claudia Struzzi ◽  
Mattia Scardamaglia ◽  
Axel Hemberg ◽  
Luca Petaccia ◽  
Jean-François Colomer ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Plasma Treatment ◽  
Carbon Nanostructures ◽  
Chemical Properties ◽  
Spectroscopic Techniques ◽  
Multiwalled Carbon ◽  
Desorption Process ◽  
Vertically Aligned ◽  
Physical And Chemical

Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

scholarly journals Synthesis and Characterization of Porous CaCO3 Vaterite Particles by Simple Solution Method

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4425
Author(s):  
Renny Febrida ◽  
Arief Cahyanto ◽  
Ellyza Herda ◽  
Vanitha Muthukanan ◽  
Nina Djustiana ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Times ◽  
Chemical Properties ◽  
Raw Material ◽  
Porous Microsphere ◽  
Different Temperatures ◽  
Mixing Method ◽  
Physical And Chemical ◽  
And Chemical Properties

Appropriately engineered CaCO3 vaterite has interesting properties such as biodegradability, large surface area, and unique physical and chemical properties that allow a variety of uses in medical applications, mainly in dental material as the scaffold. In this paper, we report the synthesis of vaterite from Ca(NO3)2·4H2O without porogen to obtain a highly pure and porous microsphere for raw material of calcium phosphate as the scaffold in our future development. CaCO3 properties were investigated at two different temperatures (20 and 27 °C) and stirring speeds (800 and 1000 rpm) and at various reaction times (5, 10, 15, 30, and 60 min). The as-prepared porous CaCO3 powders were characterized by FTIR, XRD, SEM, TEM, and BET methods. The results showed that vaterite with purity 95.3%, crystallite size 23.91 nm, and porous microsphere with lowest pore diameter 3.5578 nm was obtained at reaction time 30 min, temperature reaction 20 °C, and stirring speed 800 rpm. It was emphasized that a more spherical microsphere with a smaller size and nanostructure contained multiple primary nanoparticles received at a lower stirring speed (800 rpm) at the reaction time of 30 min. One of the outstanding results of this study is the formation of the porous vaterite microsphere with a pore size of ~3.55 nm without any additional porogen or template by using a simple mixing method.

scholarly journals NOVEL PALM OIL BASED POLYOLS WITH AMINE FUNCTIONALITY SYNTHESIS VIA RING OPENING REACTION OF EPOXIDIZED PALM OIL

2018 ◽  
Vol 80 (6) ◽  
Author(s):  
Sabrina Soloi ◽  
Rohah Abdul Majid ◽  
Abdul Razak Rahmat
Keyword(s):  
Reaction Time ◽  
Palm Oil ◽  
Ring Opening ◽  
Market Price ◽  
Chemical Properties ◽  
Oxirane Ring ◽  
Epoxidized Palm Oil ◽  
Ring Opening Reaction ◽  
Twin Band ◽  
Physical And Chemical

In polymer chemistry, polyol usually used as starting materials for polyurethane (PU) production in which upon reacted with isocyanate will affect the physical and chemical properties of the obtained PU. Polyols that are mostly derived from petrochemical resources are facing issues such as depletion of petroleum sources as well as the increasing in market price. Ring opening reaction (ROR) of epoxidized palm oil (EPO) had been carried out using isopropanolamine (IPA) to impart polyol with amine functionality. The effect of reaction time on the opening of oxirane ring was investigated. FTIR spectra showed that the oxirane ring opening of EPO can occur at 6 hours reaction time, corresponding to the deacreasing intensity of  oxirane COO twin band at 824-830 cm-1. The OH value of the amine- functionalized-polyol was calculated at around 240-253 mg KOH/g. By prolonging the reaction time the OH value has slightly reduced. Mass spectroscopy analysis revealed that the polyol has a molecular weight in the range of oligo-polyols (400 – 500 Da).

Properties of Sol-Gel Coating Film Synthesized from Nano Boehmite and Methyltrimethoxysilane

2007 ◽  
Vol 544-545 ◽  
pp. 1041-1044 ◽  
Author(s):  
In Hye Myung ◽  
Myeong Sang Ahn ◽  
Dong Pil Kang
Keyword(s):  
Reaction Time ◽  
Flat Surface ◽  
Sol Gel ◽  
Chemical Properties ◽  
Spherical Shape ◽  
Coating Film ◽  
Physical And Chemical Properties ◽  
Coating Films ◽  
Physical And Chemical ◽  
And Chemical Properties

Several sol solutions were synthesized by using two kinds of nanosized boehmite and methyltrimethoxysilane (MTMS) according to the changing amount of MTMS at different reaction time. To understand their physical and chemical properties, sol-gel coating films were fabricated on glass. The sol solutions were prepared from boehmite of spherical shape (boehmite1)/MTMS and mixed boehmites of spherical and fibrous shapes (boehmite2)/MTMS. The soluble stability of boehmite1/MTMS was observed in the sol solution left for 24 h, however, that of boehmite2/MTMS was observed in the sol solution left for 48 h. The contact angle of sol-gel coating films from boehmite/MTMS increased with MTMS contents and reaction time. The films formed a flat surface with the increasing MTMS contents and decreasing reaction time. The electrical resistivity of films increased with MTMS contents. The thermal degradation of films occurred at approximately 400 oC.

scholarly journals Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Mohamed E. Assal ◽  
Mufsir Kuniyil ◽  
Mohammed Rafi Shaik ◽  
Mujeeb Khan ◽  
Abdulrahman Al-Warthan ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Surface Area ◽  
Selective Oxidation ◽  
Zinc Oxide Nanoparticles ◽  
Specific Activity ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Oxide Nanoparticles ◽  
Oxidation Of Alcohols ◽  
Aerial Oxidation

Zinc oxide nanoparticles doped manganese carbonate catalysts [X% ZnOx–MnCO3] (where X = 0–7) were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [X% ZnOx–MnO2] and [X% ZnOx–Mn2O3]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnOx–MnCO3 calcined at 300°C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnOx–MnCO3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol·g−1·h−1) and 390.6 turnover frequency (TOF). The specific activity obtained is the highest so far (to the best of our knowledge) compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnOx nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.

Gases as ingredients of medicines

2020 ◽  
Vol 18 (4) ◽  
Author(s):  
Aleksandr L. Urakov
Keyword(s):  
Biological Activity ◽  
Specific Activity ◽  
Chemical Properties ◽  
Chemical Activity ◽  
Main Ingredient ◽  
Water Solutions ◽  
Body Tissues ◽  
Physico Chemical ◽  
Patent Literature ◽  
Physical And Chemical

The literature review shows that today all over the world reference books on medicines, state Pharmacopoeia, textbooks on pharmacology and pharmacy, as well as scientific articles published in pharmaceutical and pharmacological scientific journals, contain information about medicines without taking into account the presence of gases in them. The effect of each drug is historically considered on the example of the action of its main ingredient without taking into account the action of other ingredients, namely, auxiliary, formative agents and means that change the color, taste and smell of drugs. At the same time, the biological activity of the main ingredients is traditionally considered as the activity of highly purified chemical reagents with the brand pure for analysis. The results of a review of scientific and patent literature have shown that in natural conditions, due to high atmospheric air pressure, air gases are always present in all substances, including liquid and solid drugs, as well as human and animal body tissues. Usually, air gases remain invisible to the naked eye. It was found that the composition and quantity of gases in medicines affect their mechanical, physical, chemical and physico-chemical properties, which give the drugs a non-specific activity when applied topically. Using the example of water, solutions and tablets, it is shown how the content of gases in them changes under vacuum, low, normal and high atmospheric pressure, and how this changes their physical and chemical properties. It is shown that the regulation of the content of gases in water, solutions and tablets of medicines allows to regulate their mass, volume, specific gravity, porosity and non-specific physical and chemical activity of medicines when applied topically. It is shown that air and individual gases have biological activity, so they can determine the mechanism of action of drugs. Recipes of new medicines in which gas is an auxiliary, formative or main ingredient are given. Itis proposed to include gases in the formulation of medicines, as well as to control the gas composition ofmedicines as an indicator of their quality and a factor of their physical and chemical activity, which can determine the type of medicines local action.

Purification of a Highly Potent Heparin-Like Anticoagulant from Healthy Human Plasma

1979 ◽  
Author(s):  
Robert H. Yue ◽  
Toby Starr ◽  
Menard M. Gertler
Keyword(s):  
Human Plasma ◽  
Specific Activity ◽  
Anticoagulant Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Deae Cellulose ◽  
Chemical Properties ◽  
Healthy Human ◽  
Naturally Occurring ◽  
Salt Gradient ◽  
Physical And Chemical

A highly potent-heparin-like anticoagulant (accelerator) has been purified from citrated healthy human plasma. After heat defibrination and BaSO4. treatment on the plasma, the accelerator was adsorbed onto a DEAE-cellulose column and elution was achieved using a high ionic strength linear buffered salt gradient. The eluted accelerator was further purified by polyacrylamide gel electrophoresis. The purified accelerator can accelerate the inhibition of thrombin by antithrombin III and has a specific activity of 226 heparin units/mg of carbohydrate. The accelerator contains a small amount of protein-like material. The amount of accelerator present in healthy human blood is extremely small and can only be first detected in the concentrate after the DEAE-cellu-lose chromatography. A mere 0.5 mg of the purified accelerator is obtained from 100 ml of human plasma. Concomitant with this investigation, a second heparin-like substance also has been purified but has very low anticoagulant activity in terms of heparin units. The naturally occurring accelerator may function as heparin in the circulating blood and its level in blood may have a clinical significance in thrombotic vascular disease. Further work on its physical and chemical properties is now in progress.

Sign in / Sign up

Export Citation Format

Share Document