scholarly journals Low temperature and limited water activity reveal a pathway to magnesite via amorphous magnesium carbonate

2020 ◽  
Vol 56 (81) ◽  
pp. 12154-12157
Author(s):  
Sebastian T. Mergelsberg ◽  
Sebastien N. Kerisit ◽  
Eugene S. Ilton ◽  
Odeta Qafoku ◽  
Christopher J. Thompson ◽  
...  
Keyword(s):  
Low Temperature ◽  
Water Activity ◽  
Reaction Pathway ◽  
Magnesium Carbonate

Experiments at low H2O activity and 25 °C reveal a new reaction pathway to magnesite via amorphous magnesium carbonate during the thin H2O film carbonation of forsterite in water-bearing liquid CO2.

Effect of Gamma Irradiation on the Survival of Pathogens in Kwamegi, a Traditional Korean Semidried Seafood

2003 ◽  
Vol 66 (11) ◽  
pp. 2093-2096 ◽  
Author(s):  
S. P. CHAWLA ◽  
D. H. KIM ◽  
C. JO ◽  
J. W. LEE ◽  
H. P. SONG ◽  
...  
Keyword(s):  
Low Temperature ◽  
Salmonella Typhimurium ◽  
Water Activity ◽  
Pathogenic Bacteria ◽  
Radiation Sensitivity ◽  
E Coli ◽  
Public Health Significance ◽  
Irradiation Treatment ◽  
Test Organisms ◽  
Health Significance

Kwamegi (semidried raw Pacific saury) is traditional seafood available in Korea. It has water activity in the range of 0.90 to 0.95. Spoilage and the growth of most pathogenic bacteria is retarded because of low water activity, low temperature, and packaging. However, it is contaminated with bacteria of public health significance and poses a hazard to the consumer because it is consumed raw without any cooking. The effectiveness of these hurdles in preventing the growth of Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, and Escherichia coli and the efficacy of irradiation treatment in eliminating these bacteria from kwamegi using inoculated pack studies was examined. Radiation sensitivity of S. aureus, B. cereus, Salmonella Typhimurium, and E. coli in kwamegi was investigated. D10-values of these organisms in kwamegi were 590 ± 13.6, 640 ± 14.9, 560 ± 45.4, and 550 ± 8.6 Gy, respectively. The growth of all four test organisms inoculated into these foods during 4 weeks of storage at an ambient winter temperature (ranging from −5°C to +5°C) was recorded. All four pathogens (inoculated at 106 CFU/g) were eliminated by irradiation at 4 kGy. These studies unequivocally demonstrate that irradiation, with a combination of low water activity and low temperature, results in microbiologically safe kwamegi.

scholarly journals Acid/Base-Treated Activated Carbon Catalysts for the Low-Temperature Endothermic Cracking of N-Dodecane with Applications in Hypersonic Vehicle Heat Management Systems

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1149
Author(s):  
Kyoung Ho Song ◽  
Soon Kwan Jeong ◽  
Byung Hun Jeong ◽  
Kwan-Young Lee ◽  
Hak Joo Kim
Keyword(s):  
Activated Carbon ◽  
Low Temperature ◽  
Reaction Pathway ◽  
Coke Formation ◽  
Superior Performance ◽  
Light Olefins ◽  
Management Systems ◽  
Acid Base ◽  
Heat Management ◽  
Carbon Catalysts

Hypersonic aircrafts suffer from heat management problems caused by the air friction produced at high speeds. The supercritical catalytic cracking of fuel is endothermic and can be exploited to remove heat from the aircraft surfaces using specially designed heat management systems. Here, we report that an acid/base-treated activated carbon (AC) catalyst shows superior performance to the conventional ZSM-5 catalyst at 4 MPa and 450 °C. Further, under these conditions, coke formation is thermodynamically avoided. Of the prepared catalysts, the AC catalyst treated with NaOH and subsequently with HNO3 (denoted AC-3Na-N) was the most active catalyst, showing the highest selectivity toward light olefins and best heat sink capacity. The acid/base-treated ACs and ZSM-5 catalysts were characterized by scanning transmission electron microscopy, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption, and Fourier-transform infrared spectroscopy measurements. Characterization reveals the importance of acid strength and density in promoting the cracking reaction pathway to light olefins observed over the acid/base-treated AC catalysts, which show comparable activity at 450 °C to that of the ZSM-5 catalyst operated above 550 °C. The low-temperature activity suppressed coke and aromatic compound (coke precursors) formation. The stability of the acid/base-treated activated carbon catalysts was confirmed over a time-on-stream of 30 min.

Observation of two oxa-azabicyclo[2.2.0]hexenone intermediates along the reaction pathway of the photochemical isomerization of 1,3-oxazin-6-ones

1981 ◽  
Vol 59 (15) ◽  
pp. 2328-2333 ◽  
Author(s):  
Paul De Mayo ◽  
Alan C. Weedon ◽  
Ralph W. Zabel
Keyword(s):  
Low Temperature ◽  
Reaction Pathway ◽  
H Nmr ◽  
Photochemical Isomerization

Irradiation of 4-methyl-2-phenyl-1,3-oxazin-6-one, 1, yields a photochemical equilibrium between 1 and 2-methyl-4-phenyl-1,3-oxazin-6-one, 2. The isomerization proceeds through two intermediates, the oxa-azabicyclo[2.2.0]hexenones 3 and 4, both of which can be observed spectroscopically (ir, uv, 1H nmr) at low temperature.

Insights into the reaction pathway of n-butane conversion over HZSM-5 zeolite at low temperature

2019 ◽  
Vol 584 ◽  
pp. 117135 ◽  
Author(s):  
Pengzhao Wang ◽  
Wenfang Zhang ◽  
Haibo Zhu ◽  
Pei Yuan ◽  
Chaohe Yang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Reaction Pathway ◽  
Butane Conversion

Differences Between Aspergillus flavus Strains in Growth and Aflatoxin B1 Production in Relation to Water Activity and Temperature

1977 ◽  
Vol 40 (11) ◽  
pp. 778-781 ◽  
Author(s):  
M. D. NORTHOLT ◽  
H. P. van EGMOND ◽  
W. E. PAULSCH
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Water Activity ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Toxin Production ◽  
Fast Growth ◽  
Temperature Optimum ◽  
Agar Media ◽  
Stimulation Of

The optimum and limiting conditions of water activity (aw) and temperature for growth of and aflatoxin B1 production by various Aspergillus flavus strains were determined. Agar media were used in which the aw was adjusted by addition of sucrose or glycerine. Optimum temperatures for aflatoxin B1 production at high aw varied with the strain tested being 13–16, 16–24, or 31 C. Strains with a low temperature optimum for aflatoxin B1 production showed fast growth at 37 C without aflatoxin B1 production. A reduced aw (0.95 and less) together with a moderate or low temperature inhibited toxin production more than growth. However, at a high temperature one strain showed stimulation of aflatoxin B1 production on the glycerine medium at reduced aw No differences were noted between aflatoxinpositive and aflatoxin-negative strains with respect to growth under various conditions.

Survival and Recovery ofSalmonella entericaSerovar Typhimurium DT104 at Low Temperature and Water Activity in a Broth System

2006 ◽  
Vol 3 (4) ◽  
pp. 375-383 ◽  
Author(s):  
Kathleen J. Kinsella ◽  
Tara A. Rowe ◽  
Ian S. Blair ◽  
David A. McDowell ◽  
James J. Sheridan
Keyword(s):  
Low Temperature ◽  
Water Activity

Low Temperature Synthesis of MO2C/W2C Superlattices via Ultra-Thin Modulated Reactants

1996 ◽  
Vol 434 ◽  
Author(s):  
Christopher D. Johnson ◽  
David C. Johnson
Keyword(s):  
Low Temperature ◽  
Binary Systems ◽  
Reaction Pathway ◽  
Synthesis Method ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Initial Reactant ◽  
Repeat Units ◽  
Superlattice Period ◽  
Modulation Length

AbstractWe report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo2C and W2C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperature(500 and 600°C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 Å. This information was used to form Mo2C/W2C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices.

scholarly journals Novel aqueous amine looping approach for the direct capture, conversion and storage of CO2 to produce magnesium carbonate

2020 ◽  
Vol 4 (3) ◽  
pp. 1265-1275 ◽  
Author(s):  
Meishen Liu ◽  
Hassnain Asgar ◽  
Soenke Seifert ◽  
Greeshma Gadikota
Keyword(s):  
Low Temperature ◽  
Magnesium Carbonate ◽  
Direct Capture ◽  
And Storage

Aqueous amine solvents (e.g., monoethanolamine) coupled with reactive alkaline sorbents (e.g., MgO) favor low temperature CO2 removal as solid carbonates.

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