scholarly journals Derivatization of Levoglucosan for Compound-Specific δ13C Analysis by Gas Chromatography/Combustion/Isotope Ratio Mass Spectrometry

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dongling Zhang ◽  
Swe Swe Aung ◽  
Yong Han ◽  
Yanlin Zhang ◽  
Yingjun Chen ◽  
...  
Keyword(s):  
Combustion Process ◽  
Volume Ratio ◽  
Isotope Ratio Mass Spectrometry ◽  
Molar Ratio ◽  
Thermal Decomposition Product ◽  
Carbon Isotopic ◽  
Different Temperatures ◽  
Minimum Number ◽  
C Value ◽  
Excellent Reproducibility

Levoglucosan is a thermal decomposition product of cellulose in particulate matter. δ13C value of levoglucosan could be used in studying the combustion mechanisms and chemical pathways. In order to introduce a minimum number of carbon atoms, based on the stereostructure of levoglucosan, a two-step derivatization method with methylboronic acid and MSTFA was developed and carefully optimized. The recommended reaction temperature is 70°C; the reaction time is 60 min for MBA and 120 min for MSTFA derivatization; and the molar ratio of levoglucosan : MBA : MSTFA is 1 : 1: 100 and 1 : 1: 120 and the reagent volume ratio of MSTFA : pyridine is between 1 : 3 and 1 : 4. The developed method achieved excellent reproducibility and high accuracy. The differences in the carbon isotopic compositions of the target boronate trimethysilylated derivative between the measured and calculated ranged from 0.09 to 0.36‰. The standard deviation of measured δ13C value of levoglucosan was between 0.22 and 0.48‰. The method was applied to particle samples collected from the combustion of cellulose at four different temperatures. δ13C values of levoglucosan in particle samples generated from a self-made combustion setup suggesting that combustion temperature play a little role on isotope fractionation of levoglucosan, although 13C enriched in levoglucosan during the combustion process.

scholarly journals Isotopic Evidence for Long-Distance Connections of the AD Thirteenth-Century Promontory Caves Occupants

2021 ◽  
pp. 1-23
Author(s):  
Jessica Z. Metcalfe ◽  
John W. Ives ◽  
Sabrina Shirazi ◽  
Kevin P. Gilmore ◽  
Jennifer Hallson ◽  
...  
Keyword(s):  
Material Culture ◽  
Thirteenth Century ◽  
Isotopic Analysis ◽  
Bone Collagen ◽  
Turnover Rates ◽  
Long Distance ◽  
Carbon Isotopic ◽  
Local Plant ◽  
Northern Utah ◽  
C Value

The Promontory caves (Utah) and Franktown Cave (Colorado) contain high-fidelity records of short-term occupations by groups with material culture connections to the Subarctic/Northern Plains. This research uses Promontory and Franktown bison dung, hair, hide, and bone collagen to establish local baseline carbon isotopic variability and identify leather from a distant source. The ankle wrap of one Promontory Cave 1 moccasin had a δ13C value that indicates a substantial C4 component to the animal's diet, unlike the C3 diets inferred from 171 other Promontory and northern Utah bison samples. We draw on a unique combination of multitissue isotopic analysis, carbon isoscapes, ancient DNA (species and sex identification), tissue turnover rates, archaeological contexts, and bison ecology to show that the high δ13C value was not likely a result of local plant consumption, bison mobility, or trade. Instead, the bison hide was likely acquired via long-distance travel to/from an area of abundant C4 grasses far to the south or east. Expansive landscape knowledge gained through long-distance associations would have allowed Promontory caves inhabitants to make well-informed decisions about directions and routes of movement for a territorial shift, which seems to have occurred in the late thirteenth century.

scholarly journals Radiocarbon Dating of Calcined Bones: Where Does the Carbon Come from?

Radiocarbon ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 601-611 ◽  
Author(s):  
A Zazzo ◽  
J-F Saliège ◽  
A Person ◽  
H Boucher
Keyword(s):  
Radiocarbon Dating ◽  
Tooth Enamel ◽  
Skeletal Remains ◽  
Archaeological Sites ◽  
Carbonate Content ◽  
The Past ◽  
Mineral Fraction ◽  
Different Temperatures ◽  
C Value ◽  
Paleodietary Reconstruction

Over the past decade, radiocarbon dating of the carbonate contained in the mineral fraction of calcined bones has emerged as a viable alternative to dating skeletal remains in situations where collagen is no longer present. However, anomalously low δ13C values have been reported for calcined bones, suggesting that the mineral fraction of bone is altered. Therefore, exchange with other sources of carbon during heating cannot be excluded. Here, we report new results from analyses on cremated bones found in archaeological sites in Africa and the Near East, as well as the results of several experiments aiming at improving our understanding of the fate of mineral and organic carbon of bone during heating. Heating of modern bone was carried out at different temperatures, for different durations, and under natural and controlled conditions, and the evolution of several parameters (weight, color, %C, %N, δ13C value, carbonate content, crystallinity indexes measured by XRD and FTIR) was monitored. Results from archaeological sites confirm that calcined bones are unreliable for paleoenvironmental and paleodietary reconstruction using stable isotopes. Experimental results suggest that the carbon remaining in bone after cremation likely comes from the original inorganic pool, highly fractionated due to rapid recrystallization. Therefore, its reliability for 14C dating should be seen as close to that of tooth enamel, due to crystallographic properties of calcined bones.

Optimization and statistical analysis of sono-Fenton treated wastewater of food industry using reactor by response surface method

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vijay A. Juwar ◽  
Ajit P. Rathod
Keyword(s):  
Reaction Time ◽  
Response Surface ◽  
Food Industry ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Volume Ratio ◽  
Cod Removal ◽  
Treated Wastewater ◽  
Experimental Result ◽  
Molar Ratio

Abstract The present study deals with the treatment of complex waste (WW) treated for removal of chemical oxygen demand (COD) of the food industry by a sono-Fenton process using a batch reactor. The response surface methodology (RSM) was employed to investigate the five independent variables, such as reaction time, the molar ratio of H2O2/Fe2+, volume ratio of H2O2/WW, pH of waste, and ultrasonic density on COD removal. The experimental data was optimized. The optimization yields the conditions: Reaction time of 24 min, HP:Fe molar ratio of 2.8, HP:WW volume ratio of 1.9 ml/L, pH of 3.6 and an ultrasonic density of 1.8 W/L. The predicted value of COD was 91% and the experimental result was 90%. The composite desirability value (D) of the predicted percent of COD removal at the optimized level of variables was close to one (D = 0.991).

Preparation and Swelling Dynamics Characterization of Poly(N, N-Diethylacrylamide-Co-Itaconic Acid) Intelligent Hydrogels

2012 ◽  
Vol 490-495 ◽  
pp. 3382-3386
Author(s):  
Xiao Qi Li ◽  
Nai Yan Zhang ◽  
Jun Hai Zhang
Keyword(s):  
Itaconic Acid ◽  
Monomer Concentration ◽  
Molar Ratio ◽  
Solution Temperature ◽  
Temperature Changes ◽  
Different Temperatures ◽  
Total Monomer Concentration ◽  
Equilibrium Swelling Ratio ◽  
Composition Ratios ◽  
Response To Temperature

Poly(N,N-diethylacrylamide) (PDEA) hydrogel is known for their intelligent reversible swelling/deswelling behavior in response to temperature changes across a lower critical solution temperature (LCST) at around 31oC. In this study, itaconic acid (IA) was co-polymerized with N, N-diethylacrylamide (DEA) monomer to improve the swelling behavior and the total absorbing water. These copolymer hydrogels were prepared by changing the initial DEA/IA molar ratio and total monomer concentration. The chemical structure of hydrogels was characterized by fourier transform infrared (FTIR) spectroscopy. In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) of the hydrogels increase with the increase of IA content in the feed and the swelling dynamics behaviors of the different composition ratios of the P(DEA-co-IA) hydrogels on the different temperatures was investigated in detail.

scholarly journals Experimental determination of a mass loss of biomass pellets at different temperatures of the combustion chamber combusted in a stream of inert material

2019 ◽  
Vol 82 ◽  
pp. 01007
Author(s):  
Katarzyna Kaczyńska ◽  
Konrad Kaczyński ◽  
Piotr Pełka
Keyword(s):  
Mass Loss ◽  
Combustion Chamber ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Inert Material ◽  
Mass Rate ◽  
Different Temperatures

In the herein paper, research on the mass loss of biomass pellets is presented. The research was carried out on a specially constructed test stand. In the research three types of pellet fuels were used, which were made of oak sawdust, sunflower husk and straw. The research was carried out at three different temperatures of the combustion chamber: 850°C, 750°C and 650°C. The research was carried out without inert material and mass rate flow Gs=2,5kg/m2s and Gs=5kg/m2s. Quartz sand was the inert material. It was expected that an increase in the temperature prevailing in the combustion chamber would accelerate the process of mass loss of the biomass pellet combustion. However, the results of the experiment indicated that this is not the case in every analyzed case. The mass flow rate of inert material intensifies the combustion process and accelerates the biomass pellets made of oak sawdust mass loss, but increasing the temperature in the combustion chamber accelerates the process of biomass pellets mass loss more than the mass flow rate of inert material. Based on the experimental tests carried out, it was found that biomass can be combusted in circulating fluidized bed boilers, albeit due to the diversified chemical composition of the biomass (alkali content), the boiler should be operated in such a way as to prevent the softening and melting temperature of the ash being exceeded.

scholarly journals MD INVESTIGATIONS FOR MECHANICAL PROPERTIES OF COPPER NANOWIRES WITH AND WITHOUT SURFACE DEFECTS

2012 ◽  
Vol 09 (01) ◽  
pp. 1240003 ◽  
Author(s):  
Y. T. GU ◽  
H. F. ZHAN
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Yield Strength ◽  
Yield Point ◽  
Surface Defects ◽  
Volume Ratio ◽  
Strain Rates ◽  
Copper Nanowires ◽  
Dislocation Source ◽  
Different Temperatures

Based on the molecular dynamics (MD) method, the single-crystalline copper nanowire with different surface defects is investigated through tension simulation. For comparison, the MD tension simulations of perfect nanowire are first carried out under different temperatures, strain rates, and sizes. It has concluded that the surface–volume ratio significantly affects the mechanical properties of nanowire. The surface defects on nanowires are then systematically studied in considering different defect orientation and distribution. It is found that the Young's modulus is the insensitive of surface defects. However, the yield strength and yield point show a significant decrease due to the different defects. Different defects are observed to serve as a dislocation source.

Highly efficient Co(II) porphyrin catalysts for the extractive oxidative desulfurization of dibenzothiophene in fuel oils under mild conditions

2020 ◽  
Vol 25 (01) ◽  
pp. 24-30
Author(s):  
Deependra Tripathi ◽  
Inderpal Yadav ◽  
Himani Negi ◽  
Raj K. Singh ◽  
Vimal C. Srivastava ◽  
...  
Keyword(s):  
Oxidative Desulfurization ◽  
Volume Ratio ◽  
Fuel Oil ◽  
Molar Ratio ◽  
Mild Conditions ◽  
Reaction Optimization ◽  
Middle Distillate Fuel ◽  
Fuel Oils ◽  
Optimized Conditions ◽  
Distillate Fuel

Co(II) porphyrins have been utilized as efficient and selective catalysts for the extractive oxidative desulfurization reaction on the refractory dibenzothiophene (DBT) in [Formula: see text]-dodecane (model middle distillate fuel oil). The acetonitrile was taken as extracting polar solvent and H2O2 was used as oxidant. The reaction optimization was done with respect to DBT:catalyst molar ratio; DBT:H2O2 molar ratio; extracting solvent: CH3CN/[Formula: see text]-dodecane volume ratio; reaction temperature and time. Under the optimized conditions, a maximum of [Formula: see text]98% DBT removal was achieved by using the meso-tetrakis(4[Formula: see text] methoxyphenyl)porphyrinatocobalt(II) as catalyst under mild conditions at 50[Formula: see text]C.

Synthesis and Characterization of Crystalline FeCo Nanoparticles

2006 ◽  
Vol 6 (11) ◽  
pp. 3417-3421 ◽  
Author(s):  
Chang Woo Kim ◽  
Young Hwan Kim ◽  
Hyun Gil Cha ◽  
Don Keun Lee ◽  
Young Soo Kang
Keyword(s):  
Exchange Coupling ◽  
Chemical Method ◽  
Coupling Effect ◽  
Molar Ratio ◽  
Feco Alloy ◽  
Uniform Size ◽  
Different Temperatures ◽  
Shape Controlled ◽  
Feco Nanoparticles

The monodispersed FeCo nanoparticles were synthesized with borohydride as a reducing agent by coprecipitation method in aqueous solution. The composition and the size of FeCo nanoparticle was controlled by fitting the molar ratio of starting material, the reaction time and the falling rate. To prepare the crystallized nanoparticles, the amorphous FeCo nanoparticles were annealed at the different temperatures for 1 hr, respectively. The size of the crystalline FeCo nanoparticles was controlled in order to maintain the uniform size of 20nm. The as-annealed FeCo alloy could get the highest Ms value of the powder which has been ever synthesized by coprecipitation or other chemical method. The size- and shape-controlled crystalline FeCo nanoparticles can be applied for spring magnet in order to get exchange coupling effect.

scholarly journals Production of Biodiesel from Waste Vegetable Oil via KM Micromixer

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. F. Elkady ◽  
Ahmed Zaatout ◽  
Ola Balbaa
Keyword(s):  
Mass Spectrometry ◽  
Catalyst Concentration ◽  
Volume Ratio ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Gas Chromatography Mass Spectrometry ◽  
Waste Oil ◽  
Flow Rates ◽  
Waste Vegetable Oil ◽  
Ft Ir

The production of biodiesel from waste vegetable oils through its pretreatment followed by transesterification process in presence of methanol was investigated using a KM micromixer reactor. The parameters affecting biodiesel production process such as alcohol to oil molar ratio, catalyst concentration, the presence of tetrahydrofuran (THF) as a cosolvent, and the volumetric flow rates of inlet fluids were optimized. The properties of the produced biodiesel were compared with its parent waste oil through different characterization techniques. The presence of methyl ester groups at the produced biodiesel was confirmed using both the gas chromatography-mass spectrometry (GC-MS) and the infrared spectroscopy (FT-IR). Moreover, the thermal analysis of the produced biodiesel and the comparable waste oil indicated that the product after the transesterification process began to vaporize at 120°C which makes it lighter than its parent oil which started to vaporize at around 300°C. The maximum biodiesel production yield of 97% was recorded using 12 : 1 methanol to oil molar ratio in presence of both 1% NaOH and THF/methanol volume ratio 0.3 at 60 mL/h flow rate.

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