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Endothermic reactions

Mahendra Kumar Trivedi, Kalyan Kumar Sethi, Parthasarathi Panda, Snehasis Jana
OBJECTIVE: Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. MATERIALS AND METHODS: The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques...
January 2017: International Journal of Pharmaceutical Investigation
M Takacs, S Ackermann, A Bonk, M Neises-von Puttkamer, Ph Haueter, J R Scheffe, U F Vogt, A Steinfeld
Thermochemical splitting of CO2 via a ceria-based redox cycle was performed in a solar-driven thermogravimetric analyzer. Overall reaction rates, including heat and mass transport, were determined under concentrated irradiation mimicking realistic operation of solar reactors. Reticulated porous ceramic (RPC) structures and fibers made of undoped and Zr(4+)-doped CeO2, were endothermally reduced under radiative fluxes of 1280 suns in the temperature range 1200-1950 K and subsequently re-oxidized with CO2 at 950-1400 K...
April 2017: AIChE Journal
Marcin Gronowski, Piotr Eluszkiewicz, Thomas Custer
Formyl cyanide has been detected toward Sgr B2 making this chemical and its potential isomers of astrophysical interest. We calculated the precise energies of the five most stable structural isomers of formyl cyanide and found that formyl isocyanide and 2H-azirin-2-one are less stable than formyl cyanide by 55 and 125 kJ/mol, respectively. We present our ab initio coupled cluster predictions of the spectroscopic parameters relevant to their gas-phase rotational and vibrational spectroscopy. Parameters include ground vibrational state rotational constants, centrifugal distortion parameters, equilibrium electric dipole moments, and nuclear quadrupole coupling constants...
April 24, 2017: Journal of Physical Chemistry. A
David L Swanson, Andrew E McKechnie, François Vézina
Adaptive explanations for both high and low body mass-independent basal metabolic rate (BMR) in endotherms are pervasive in evolutionary physiology, but arguments implying a direct adaptive benefit of high BMR are troublesome from an energetic standpoint. Here, we argue that conclusions about the adaptive benefit of BMR need to be interpreted, first and foremost, in terms of energetics, with particular attention to physiological traits on which natural selection is directly acting. We further argue from an energetic perspective that selection should always act to reduce BMR (i...
April 11, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Peilin Liao, Rachel B Getman, Randall Q Snurr
Activation of the C-H bonds in ethane to form ethanol is a highly desirable, yet challenging, reaction. Metal-organic frameworks (MOFs) with open Fe sites are promising candidates for catalyzing this reaction. One advantage of MOFs is their modular construction from inorganic nodes and organic linkers, allowing for flexible design and detailed control of properties. In this work, we studied a series of single-metal atom Fe model systems with ligands that are commonly used as MOF linkers and tried to understand how one can design an optimal Fe catalyst...
April 10, 2017: ACS Applied Materials & Interfaces
Arush Sharma, Gaurav Sharma, Mu Naushad, Ayman A Ghfar, Deepak Pathania
The present study was attempted to ascertain the possible application of activated carbon as cost effective and eco-friendly adsorbent prepared via microwave (MW) assisted chemical activation. The activated carbon was characterized using different techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM). The various adsorption parameters have been optimized to examine the viability of activated carbon as a plausible sorbent for the remediation of Congo red (CR) dye from aquatic system...
April 7, 2017: Environmental Technology
Manoj Acharya, Satyaki Mishra, Rudra N Sahoo, Subrata Mallick
Assessment of interactions of ibuprofen and magnesium trisilicate after co-processing has been carried out by infrared spectroscopy. Dry-state ball-milling and, aqueous state kneading and freeze-drying were performed. FTIR spectroscopy of co-processed materials described acid-base reaction between the carboxylic acid containing ibuprofen to a significant extent. Increased absorbance of carboxylate peak accompanied by a consistently reduced absorbance of the carbonyl acid peak was evident. Absorbance of carboxylate peak was more in freeze-dried sample compared to milled product...
2017: Acta Chimica Slovenica
Chaitanya K Narula, Lawrence F Allard, Melanie Moses-DeBusk, G Malcom Stocks, Zili Wu
New convenient wet-chemistry synthetic routes have made it possible to explore catalytic activities of a variety of single supported atoms, however, the single supported atoms on inert substrates (e.g. alumina) are limited to adatoms and cations of Pt, Pd, and Ru. Previously, we have found that single supported Pt atoms are remarkable NO oxidation catalysts. In contrast, we report that Pd single atoms are completely inactive for NO oxidation. The diffuse reflectance infra-red spectroscopy (DRIFTS) results show the absence of nitrate formation on catalyst...
April 3, 2017: Scientific Reports
Marie-Paule Bassez
In this article, anoxic and oxic hydrolyses of rocks containing Fe (II) Mg-silicates and Fe (II)-monosulfides are analyzed at 25 °C and 250-350 °C. A table of the products is drawn. It is shown that magnetite and hydrogen can be produced during low-temperature (25 °C) anoxic hydrolysis/oxidation of ferrous silicates and during high-temperature (250 °C) anoxic hydrolysis/oxidation of ferrous monosulfides. The high-T (350 °C) anoxic hydrolysis of ferrous silicates leads mainly to ferric oxides/hydroxides such as the hydroxide ferric trihydroxide, the oxide hydroxide goethite/lepidocrocite and the oxide hematite, and to Fe(III)-phyllosilicates...
March 31, 2017: Origins of Life and Evolution of the Biosphere
Chaw Yee Beh, Chee Wun How, Jhi Biau Foo, Jia Ning Foong, Gayathri Thevi Selvarajah, Abdullah Rasedee
Tamoxifen (TAM) has been used in the treatment of breast cancers and is supplemented with erythropoietin (EPO) to alleviate the cancer-related anemia. The purported deleterious effects caused by the use of EPO with chemotherapeutic agents in the treatment of cancer-related anemia vary across studies and remain controversial. The use of nanoparticles as a drug delivery system has the potential to improve the specificity of anticancer drugs. In this study, we simultaneously incorporated two pharmacological active ingredients in one nanocarrier to develop EPO-conjugated TAM-loaded lipid nanoparticles (EPO-TAMNLC), a targeted delivery system, to enhance the cytotoxic activity while reducing the side effects of the ingredients...
2017: Drug Design, Development and Therapy
Xiao-Shui Li, Yu-Han Fan, Shou-Wen Zhang, Shi-Hua Qi
A novel amino-functionalized magnetic silica (Fe3O4@SiO2-NH2) was easily prepared via a one-step method integrating the immobilization of 3-aminopropyltriethoxysilane with a sol-gel process of tetraethyl orthosilicate into a single process. This showed significant improvement in the adsorption capacity of anionic dyes. The product (Fe3O4@SiO2-NH2) was characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, zeta potential and vibrating sample magnetometry...
March 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Ming-Chung Yang, Akhilesh K Sharma, W M C Sameera, Keiji Morokuma, Ming-Der Su
The addition reaction of M(Cl)(CO)(PPh3)2 (M = Rh, Ir) and M(PPh3)2 (M = Pd, Pt) fragments with X@C60 (X = 0, Li(+)) were characterized by density functional theory (DFT) and the artificial force-induced reaction (AFIR) method. The calculated free energy profiles suggested that the η(2)[6:6]-addition is the most favorable reaction, which is consistent with the experimental observations. In the presence of Li(+) ion, the reaction is highly exothermic, leading to η(2)[6:6] product of L4IrLi(+)@C60. In contrast, an endothermic reaction was observed in the absence of a Li(+) ion...
March 24, 2017: Journal of Physical Chemistry. A
Phuong D Dau, Phuong V Dau, Linfeng Rao, Attila Kovács, John K Gibson
The gas-phase uranyl peroxide dimer, [(UO2)2(O2)(L)2](2+) where L = 2,2'-trifluoroethylazanediyl)bis(N,N'-dimethylacetamide), was synthesized by electrospray ionization of a solution of UO2(2+) and L. Collision-induced dissociation of this dimer resulted in endothermic O atom elimination to give [(UO2)2(O)(L)2](2+), which was found to spontaneously react with water via exothermic hydrolytic chemisorption to yield [(UO2)2(OH)2(L)2](2+). Density functional theory computations of the energies for the gas-phase reactions are in accord with observations...
April 3, 2017: Inorganic Chemistry
Monika Wawrzkiewicz, Przemysław Bartczak, Teofil Jesionowski
A new biomaterial based on chitin and lignin was prepared and applied for the removal of hazardous dye C.I. Direct Blue 71 (DB71) from aqueous solutions and wastewaters. The dye sorption on the chitin/lignin biosorbent (Ch/L) was examined depending on the initial dye concentration (50-200mg/L), phase contact time (1-1440min), kind of auxiliaries (NaCl, Na2SO4, anionic surfactant SDS) and their concentrations (1-20g/L salts, 0.1-0.75g/L SDS), initial solution pH as well as temperature (20-50°C). The equilibrium and kinetic characteristics of C...
June 2017: International Journal of Biological Macromolecules
Daniel R Fröhlich, Martin M Maiwald, Franziska Taube, Johann Plank, Petra J Panak
The complexation of trivalent lanthanides with a commercial polycarboxylate based concrete superplasticizer (Glenium® 51) is investigated using different spectroscopic techniques. Time-resolved laser fluorescence spectroscopy (TRLFS) in combination with a charge neutralization model is used to determine temperature dependent conditional stability constants (log β'(T)) for the complexation of Eu(iii) with Glenium® 51 in 0.1 mol kg(-1) NaCl solution in the temperature range of 20-90 °C. Only one complex species is observed, and log β'(T) (given in kg per mol eq) shows a very slight increase with temperature from 7...
March 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Shaun G Ard, Oscar Martinez, Steven A Brown, Jordan C Sawyer, P B Armentrout, Albert A Viggiano, Nicholas S Shuman
The kinetics of (4)Fe(+)(CO)n=0-2 + O2 are measured under thermal conditions from 300-600 K using a selected-ion flow tube apparatus. Both the bare metal and n = 2 cations are inert to reaction over this temperature range, but (4)Fe(+)(CO) reacts rapidly (k = 3.2 ± 0.8 × 10(-10) cm(3) s(-1) at 300 K, 52% of the collisional rate coefficient) to form FeO(+) + CO2. This is an example of the oxidation of CO by O2 occurring entirely on a single non-noble metal atom. The reaction of the bare metal reaction is known to be endothermic, such that this result is expected; however, the n = 2 reaction has highly exothermic product channels available, such that the lack of reaction is surprising in light of the n = 1 reactivity...
March 9, 2017: Physical Chemistry Chemical Physics: PCCP
Janina Kuduk-Jaworska, Jerzy J Jański, Szczepan Roszak
The results of computational simulation of reaction courses mimicking the transformation of carboplatin from pro-drug into its active shape, responsible for cytotoxic effect, are reported. Implementing the density functional theory (DFT) calculations and the supermolecular approach, we explored the pathways representing two disparate models of carboplatin bioactivation: (1) based on paradigm of carboplatin aquation, and (2) based on new hypothesis that transformation is controlled by electron-transfer processes...
February 11, 2017: Journal of Inorganic Biochemistry
Kate L Henderson, Mingjie Li, Salette Martinez, Edwin A Lewis, Robert P Hausinger, Joseph P Emerson
BACKGROUND: TauD is a nonheme iron(II) and α-ketoglutarate (αKG) dependent dioxygenase, and a member of a broader family of enzymes that oxidatively decarboxylate αKG to succinate and carbon dioxide thereby activating O2 to perform a range of oxidation reactions. However before O2 activation can occur, these enzymes bind both substrate and cofactor in an effective manner. Here the thermodynamics associated with substrate and cofactor binding to FeTauD are explored. METHODS: Thermal denaturation of TauD and its enzyme-taurine, enzyme-αKG, and enzyme-taurine-αKG complexes are explored using circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC)...
February 15, 2017: Biochimica et Biophysica Acta
M A Ahmed, A A Brick, A A Mohamed
A new approach for removal of indigo carmine blue (IC) dye which is extensively used in jeans manufacture was successfully performed on novel mesoporous [LDH] nanoparticles prepared by sol-gel route using CTAB as shape and pore directing agent. The physicochemical features were monitored by X-ray diffraction (XRD), Fourier transformer infra-red (FTIR), N2 adsorption-desorption isotherm, Field emission electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The influence of reaction parameters affecting dye adsorption including contact time, initial dye concentration, pH and temperature were investigated...
May 2017: Chemosphere
Jaruwan Siritapetawee, Chutima Talabnin, Jarunee Vanichtanankul, Chomphunuch Songsiriritthigul, Kanjana Thumanu, Chun-Jung Chen, Nantarat Komanasin
In this study, the binding of a glycosylated serine protease (EuP-82) with human fibrinogen was investigated by the isothermal titration calorimetry (ITC). The ITC analysis indicated that the binding of EuP-82 to fibrinogen in the conditions with or without the activator (Ca(2+) ) was an exothermic reaction (dominant negative enthalpy), which tended to be driven by hydrogen bonding and van der Waals interactions. In contrast, the binding of fibrinogen-EuP-82 in the condition with the inhibitor (Zn(2+) ) was an unfavorable endothermic reaction...
February 1, 2017: Biotechnology and Applied Biochemistry
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