scholarly journals Shape memory epoxy vitrimers based on DGEBA crosslinked with dicarboxylic acids and their blends with citric acid

RSC Advances ◽  
2016 ◽  
Vol 6 (91) ◽  
pp. 88647-88655 ◽  
Author(s):  
F. I. Altuna ◽  
C. E. Hoppe ◽  
R. J. J. Williams
Keyword(s):  
Citric Acid ◽  
Thermal Treatment ◽  
Shape Memory ◽  
Dicarboxylic Acids ◽  
Epoxy Acid

The shape of epoxy–acid based vitrimers can be changed either temporarily or permanently by selecting the appropriate thermal treatment.

Citric acid facilitated thermal treatment: An innovative method for the remediation of mercury contaminated soil

2015 ◽  
Vol 300 ◽  
pp. 546-552 ◽  
Author(s):  
Fujun Ma ◽  
Changsheng Peng ◽  
Deyi Hou ◽  
Bin Wu ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Citric Acid ◽  
Thermal Treatment ◽  
Contaminated Soil ◽  
Innovative Method

THE INCREASE OF THE MARTENSITIC DEFORMATION DURING SHAPE MEMORY EFFECT IN DEFORMED TiNi

2012 ◽  
Vol 05 (01) ◽  
pp. 1250011 ◽  
Author(s):  
GEORGIY FIRSTOV ◽  
YURI KOVAL ◽  
ALEKSANDR LOTKOV ◽  
VICTOR GRISHKOV ◽  
JAN VAN HUMBEECK
Keyword(s):  
Thermal Treatment ◽  
Shape Memory ◽  
Volume Fraction ◽  
Niti Alloy ◽  
Structure Refinement ◽  
External Stress ◽  
Low Temperature Annealing ◽  
Ultrafine Structure ◽  
Hot Rolled ◽  
Memory Characteristics

The evolution of the ultrafine structure, obtained at thermal treatment below recrystallization, and its effect onto shape memory characteristics in NiTi alloy was under study. It was shown that low temperature annealing (< 0.5 Tmelt) of the hot rolled NiTi leads to the structure refinement accompanied by the growth in accumulated martensite deformation. It was suggested that this is possible due to the increase of the volume fraction of martensite crystals properly oriented in respect to external stress.

scholarly journals Sol-gel synthesis of α-Al2O3 with enhanced porosity via dicarboxylic acid templating

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Simon Carstens ◽  
Christian Splith ◽  
Dirk Enke
Keyword(s):  
Citric Acid ◽  
Thermal Analyses ◽  
Sol Gel ◽  
Dicarboxylic Acids ◽  
Precise Control ◽  
Sol Gel Process ◽  
Successful Establishment ◽  
The One ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

AbstractOne of the major routes to synthesize macroporous α-Al2O3 is the sol-gel process in presence of templates. Templates include polymers as well as carboxylic acids, such as citric acid. By careful choice of the template, pore diameters can be adjusted between 110 nm and several µm. We report the successful establishment of plain short-chain dicarboxylic acids (DCA) as porogenes in the sol-gel synthesis of macroporous α-Al2O3. By this extension of the recently developed synthesis route, a very precise control of pore diameters is achieved, in addition to enhanced macropore volumes in α-Al2O3. The formation mechanism thereof is closely related to the one postulated for citric acid, as thermal analyses show. However, since branching in the DCA-linked alumina nuclei is not possible, close monomodal pore width distributions are attained, which are accompanied by enhanced pore volumes. This is a significant improvement in terms of controlled enhanced porosity in the synthesis of macroporous α-Al2O3.

scholarly journals The ms2io6A37 Modification of tRNA inSalmonella typhimurium Regulates Growth on Citric Acid Cycle Intermediates

1998 ◽  
Vol 180 (12) ◽  
pp. 3144-3151 ◽  
Author(s):  
Britt C. Persson ◽  
Ólafur Ólafsson ◽  
Hans K. Lundgren ◽  
Lars Hederstedt ◽  
Glenn R. Björk
Keyword(s):  
Escherichia Coli ◽  
Citric Acid ◽  
Salmonella Typhimurium ◽  
Gene Product ◽  
Respiratory Chain ◽  
Citric Acid Cycle ◽  
Dicarboxylic Acids ◽  
Acid Cycle ◽  
E Coli ◽  
Isopentenyl Adenosine

ABSTRACT The modified nucleoside 2-methylthio-N-6-isopentenyl adenosine (ms2i6A) is present in position 37 (adjacent to and 3′ of the anticodon) of tRNAs that read codons beginning with U except tRNA I,V Ser inEscherichia coli. In Salmonella typhimurium, 2-methylthio-N-6-(cis-hydroxy)isopentenyl adenosine (ms2io6A; also referred to as 2-methylthio cis-ribozeatin) is found in tRNA, most likely in the species that have ms2i6A in E. coli. Mutants (miaE) of S. typhimurium in which ms2i6A hydroxylation is blocked are unable to grow aerobically on the dicarboxylic acids of the citric acid cycle. Such mutants have normal uptake of dicarboxylic acids and functional enzymes of the citric acid cycle and the aerobic respiratory chain. The ability of S. typhimurium to grow on succinate, fumarate, and malate is dependent on the state of modification in position 37 of those tRNAs normally having ms2io6A37 and is not due to a second cellular function of tRNA (ms2io6A37)hydroxylase, themiaE gene product. We suggest that S. typhimurium senses the hydroxylation status of the isopentenyl group of the tRNA and will grow on succinate, fumarate, or malate only if the isopentenyl group is hydroxylated.

scholarly journals A predictive group-contribution model for the viscosity of aqueous organic aerosol

2019 ◽  
Author(s):  
Natalie R. Gervasi ◽  
David O. Topping ◽  
Andreas Zuend
Keyword(s):  
Citric Acid ◽  
Dicarboxylic Acids ◽  
Organic Aerosol ◽  
Thermodynamic Activity ◽  
Pure Component ◽  
Group Contribution ◽  
Organic Mixtures ◽  
Wide Range ◽  
Group Contribution Model ◽  
Mixture Viscosity

Abstract. The viscosity of primary and secondary organic aerosol (SOA) has important implications for the processing of aqueous organic aerosol phases in the atmosphere, their involvement in climate forcing, and transboundary pollution. Here we introduce a new thermodynamics-based group-contribution model, which is capable of accurately predicting the dynamic viscosity of a mixture over several orders of magnitude (~ 10−3 to > 1012 Pa s) as a function of temperature and mixture composition, accounting for the effect of relative humidity on aerosol water content. The mixture viscosity modelling framework builds on the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients) for predictions of liquid mixture non-ideality, including liquid–liquid phase separation, and the calorimetric glass transition temperature model by DeRieux et al. (2018) for pure-component viscosity values of organic components. Comparing this new model with simplified modelling approaches reveals that the group-contribution method is the most accurate in predicting mixture viscosity, although accurate pure-component viscosity predictions (and associated experimental data) are key and one of the main sources of uncertainties in current models, including the model presented here. Nonetheless, we find excellent agreement between the viscosity predictions and measurements for systems in which mixture constituents have a molar mass below 350 g mol−1. As such, we demonstrate the validity of the model in quantifying mixture viscosity for aqueous binary mixtures (glycerol, citric acid, sucrose, and trehalose), aqueous multicomponent mixtures (citric acid + sucrose and a mixture of nine dicarboxylic acids), and aqueous SOA surrogate mixtures derived from the oxidation of α-pinene, toluene, or isoprene. We also use the model to assess the expected change in SOA particle viscosity during idealized adiabatic air parcel transport from the surface to higher altitudes within the troposphere. This work demonstrates the capability and flexibility of our model in predicting the viscosity for organic mixtures of varying degrees of complexity and its applicability for modelling SOA viscosity over a wide range of temperatures and relative humidities.

scholarly journals Glassy aerosols with a range of compositions nucleate ice heterogeneously at cirrus temperatures

2012 ◽  
Vol 12 (18) ◽  
pp. 8611-8632 ◽  
Author(s):  
T. W. Wilson ◽  
B. J. Murray ◽  
R. Wagner ◽  
O. Möhler ◽  
H. Saathoff ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Citric Acid ◽  
Glassy State ◽  
Dicarboxylic Acids ◽  
Active Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Chemical Compositions ◽  
Tropical Tropopause ◽  
Cloud Models

Abstract. Atmospheric secondary organic aerosol (SOA) is likely to exist in a semi-solid or glassy state, particularly at low temperatures and humidities. Previously, it has been shown that glassy aqueous citric acid aerosol is able to nucleate ice heterogeneously under conditions relevant to cirrus in the tropical tropopause layer (TTL). In this study we test if glassy aerosol distributions with a range of chemical compositions heterogeneously nucleate ice under cirrus conditions. Three single component aqueous solution aerosols (raffinose, 4-hydroxy-3-methoxy-DL-mandelic acid (HMMA) and levoglucosan) and one multi component aqueous solution aerosol (raffinose mixed with five dicarboxylic acids and ammonium sulphate) were studied in both the liquid and glassy states at a large cloud simulation chamber. The investigated organic compounds have similar functionality to oxidised organic material found in atmospheric aerosol and have estimated temperature/humidity induced glass transition thresholds that fall within the range predicted for atmospheric SOA. A small fraction of aerosol particles of all compositions were found to nucleate ice heterogeneously in the deposition mode at temperatures relevant to the TTL (<200 K). Raffinose and HMMA, which form glasses at higher temperatures, nucleated ice heterogeneously at temperatures as high as 214.6 and 218.5 K respectively. We present the calculated ice active surface site density, ns, of the aerosols tested here and also of glassy citric acid aerosol as a function of relative humidity with respect to ice (RHi). We also propose a parameterisation which can be used to estimate heterogeneous ice nucleation by glassy aerosol for use in cirrus cloud models up to ~220 K. Finally, we show that heterogeneous nucleation by glassy aerosol may compete with ice nucleation on mineral dust particles in mid-latitudes cirrus.

scholarly journals Extração Hidrometalurgica do potássio presente na rocha Nefelina-Sienito, em função da variação da granulometria e aplicação de tratamento térmico.

2020 ◽  
Vol 1 (49) ◽  
pp. 129
Author(s):  
Defsson Douglas de Araújo Ferreira ◽  
Danúbio Leonardo Bernardino de Oliveira ◽  
João Batista de Sousa Santos ◽  
Vinícius Rewel do Nascimento Cordeiro
Keyword(s):  
Grain Size ◽  
Citric Acid ◽  
Chemical Composition ◽  
Thermal Treatment ◽  
Calcination Temperature ◽  
Mineral Processing ◽  
Agricultural Industry ◽  
Different Temperatures ◽  
The City

<p class="Normal1">Rocks that contain minerals with potassium in their chemical composition, such as, for example, Sienito and Nefelina-Sienito, are an alternative and potentially viable source for extraction of this element, however, for structural reasons this potassium is insoluble and can not be absorbed by plants. Considering that Brazil imports almost as much potassium as the agricultural industry requires, it is necessary to look for alternative ways and routes to take advantage of potentially producing sources. In this sense, a route of mineral processing and metallurgical extraction was proposed in order to make the K present in the Nefelina-Sienito rocks extracted in the city of Pedra Lavrada/PB soluble and usable. The methodology used was to apply thermal treatment and hydrometallurgical extraction with citric acid to analyze the solubility of potassium in two granulometric ranges defined by the granulochemical characterization carried out initially. The results of the granulochemical analysis showed that the highest concentrations of the element of interest were in the bands: retained in 200 and passed through 200 meshes. However, the results of the metallurgical extraction as a function of the different temperatures showed that the highest percentage of solubility (7.68%) was for samples with a grain size less than 200 mesh and a calcination temperature of 1000 ° C.</p>

Manufacturing of nanostructured Ti–Ni shape memory alloys by means of cold/warm rolling and annealing thermal treatment

2012 ◽  
Vol 212 (11) ◽  
pp. 2294-2304 ◽  
Author(s):  
Yann Facchinello ◽  
Vladimir Brailovski ◽  
Sergey D. Prokoshkin ◽  
Thomas Georges ◽  
Sergey M. Dubinskiy
Keyword(s):  
Thermal Treatment ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Warm Rolling
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